When I was in Arkansas I built two 10x20 double-sided lease boards on a state highway. I looked into unipole structures, but it would have taken me a long time to recoup my investment. As I recall, and this was many years ago, I priced "kits" from a company that ranged 6000-8000 in cost. The company would provide drawings and steel, and truck everything to the site. Then the rest was up to me. Though I can weld and run a crane, I would have hired someone local to do the assembly. Obviously, erecting a unipole is not cheap, as rjsigns mentioned above.
About lease boards
The income possible from leasing highway signs in the US is phenomenal. There are few other segments of the sign industry that have the potential for generating more than a fraction of the income that outdoor advertising is capable of. Having lease boards is like owning rent homes but not having to deal with tenants and their plumbing problems. I could easily have lived off the leases from ten small boards even though the rent I charged was at the low end of the spectrum, even by Arkansas standards. A friend of mine in a neighboring county borrowed the money to buy a plot of land with interstate frontage. He built a steel shop building and, right next to the building, a large double-sided, stacked sign —four faces altogether. The income from the four faces easily covered the payments on his land, building and sign structure, with income left over.
When I rented my boards, I usually asked clients to sign a two-year contract. Bulletin colors usually looked good for two years. If the client re-signed at the end of the contract I could quickly repaint the faces —or not, if they still looked good. If a repaint was needed, and the copy remained unchanged, a helper could do the work easily. He could go over the lettering with indelible pencils and then coat the board with a "pee" coat (not too thick). The indelible lines burned through the finish coat and were clearly visible for re-lettering. Sometimes the old copy was visible through a pee coat even without the indelible pencil.
If a new layout was required, I used XIM Flash Bond for blocking out, which allowed me to almost immediately finish coat the background with new bulletin color. Then it was back to the shop to make new patterns and do the lettering the next day.
If you are familiar with XIM Flash Bond, you probably know it as a fast drying metal primer. Actually, it sticks to practically anything, even porcelain faces, though it's pricey. I did not use Blocking Out White to prime my boards. It was cheaper, but it did not stick well to problem substrates. When re-coating a bulletin face, I was sometimes covering over Scotchlite, and XIM Flash Bond was much better than anything else at adhering to it.
I could not find my old paperwork from the company I mention above that provided unipole kits, so my numbers are from memory. But I remember that, when I was planning my highway bulletins, no matter how I figured it, the rent income would not justify the expense of a unipole. So I used 25' wood utility poles, wood stringers and MDO board, instead. I was able to build two boards by myself using local materials and without borrowing money. Materials were about 1100 dollars, as I recall, per structure, and I recovered the material cost in a few months from the lease of the first face. My labor cost was excessive since I didn't hire any help for either structure (my time was worth far more than a helper's). I did, however, need a hand with setting the poles for the first board—my tripod contraption for raising the poles was a failure and a sympathetic farmer set the poles for me with his backhoe. By the time I built the second board I had acquired a bucket truck and I short-chained the posts to the boom. Everything else was done by hand. I had a posthole digger, a jab digger, with10-foot handles for the holes, and I hung the signboard and stringers with the help of an ingenious product that had just appeared on the market called a "Rope Ratchet." This device was a single, locking pulley that was designed as a tie down but I used it for lifting light loads like 2x6 stringers and MDO panels, and later I found I could raise my 20-foot aluminum pick quickly and easily by hooking two Rope Ratchets on the upper rungs of the ladders, lifting each end alternately, then carrying my jacks up the ladders, placing them under the ends of the suspended pick.
The highway boards I had were not true "billboards." I never put bills, posters, on them. The proper term was "painted bulletins" (hence, the term "bulletin paint"). The outdoor advertising companies called them "painted displays." I determined from the beginning that my boards would not be used for posters, but only for paint or reflective vinyl. Posting bills is messy, disagreeable work. I tried it for a few months once, for a client that had his own boards. At the end of a day of pasting these posters, I was covered in potato glue and exhausted. I never got good at aligning the sections and I was too slow. And if a rainstorm damaged the job, I was sent a new package of posters and expected to make repairs for free. This client and I eventually parted ways and I chalked it all up as a learning experience.
The hardest part of getting into outdoor advertising is finding the locations for the signs. The spots must meet state highway restrictions, and you must find landowners willing to agree to what they may view as a nuisance on their property. They may see it as an eyesore, or as an annoying inconvenience when tilling farm ground. There is not a lot of money in it for them—you want to be able to pay them per year what your sign generates in a month, or two months, at the most.
Few highway boards are still painted, of course. They are digitally printed vinyl faces. But the relatively short lifespan of a digital print outdoors lends itself to the lease periods common to outdoor advertising.
It is of note that most sign companies are relatively small business. Only a few sign companies have attained the financial stature that they are publicly traded. And, with few exceptions, these are outdoor advertising companies. If a small shop can break into this market with just a few lease boards, or even one or two, it is almost like having an income stream without working for it.
Brad in Kansas City