Also, square foot pricing will be the death of you. It is a lazy crutch used by shops who don't want to accurately price things every time.
To the shop who offers $3.50/sq ft banners, all I have to say is I will take 1500 12" x 12" banners, hemmed and grommeted in all four corners, different artwork on each.
To me, these statements tell me you don't do much in a week's time. If one has 2 or 3 jobs going through their shop a week, your method might be Okay, but once you get to 15 to 25 jobs a week going out, you'll need a staff for your estimating alone. You need to estimate.... and a square foot is only one of the elements in the entire equation, but you must use a square footage system somewhere. Heck, that's how it's sold to you.
Also, if you called and ordered 1,500 individual foot by foot banners, I'd hang up on your @ss. There is a point where a shop minimum takes over. Ours is $165.00, so your banners would cost $165.00 each and I might add an additional $25. to each one for being a smart alec.
We're just finishing up a nice size order where the customer ordered around 675 signs. Almost each one is different and there are quite a few various sizes. Once they get down to a certain size, although we based this whole order on volume, there still is a bottom minimum. We made the magic number $29. for signs as little as 8" x 14" Once they go up a little, they went to $39 until we hit a good size, then we priced by the square foot. The most expensive sign came to $7,850. The total order was $138,000. So, if we hadn't used a crutch,
as you put it, the cost would've been much higher. This job took us about 2 months to do. We have about a week left on it, yet.