You'll need a reliable printer, vinyl plotter, laminator, RIP station, etc... a good stockpile of media / laminate / ink... and a proper workspace (temp / humidity control, storage racks, worktables, proper lighting, etc). By the time you figure in other things like your software licenses, training etc. -- it could very easily reach 100k -- not to mention the ongoing labor costs for running everything (and keeping it running). Chances are you'll need to hire someone with experience to run / maintain all the equipment and teach you / other staff how to operate it as well (if you're serious about getting things operational as quickly as possible). Expect this to take many, many months. Toss in an extra $5k/mo in overhead to cover the extra space, labor, utilities and waste. Heck, I'm a one-man show in a 1,200 sq.ft. space -- nothing fancy, even though I've been in the industry for 23 years -- and I'm sitting at just over 250k in equipment with only "some" semi-automated equipment like my XLD-170.
The companies you're buying from now likely have very good automation (crazy expensive equipment), so competing with their prices will be difficult. Trade suppliers have millions of $$ worth of equipment, large contracts and huge order volume (as such, they have really good buying power) -- they can operate on lower margins and give you better B2B prices (which is why trade suppliers exist). They are generally very good about providing consistent results and giving you predictable turnaround times, and all you have to worry about is getting them your artwork. They deal with all the extra headaches. That being said, I don't know how much volume you have or anything like that -- or how eager you are to delete most of the "free time" from your personal schedule, but I would expect your cost to print "in-house" to be higher than outsourcing. Most likely what you'd be gaining is convenience and quicker turnaround times for your customers.
Try running the numbers with 100k in equipment + $5k in monthly overhead including 1 full-time employee (we're talking a bare bones setup here! really bare bones!) and compare those numbers to what you can outsource for. I think you'll be surprised at how affordable outsourcing is.