There's a wholesale SAV and poster printing company here in Sydney who advertises direct to just about everyone via PO Boxes, and in a few magazines. Cheap as chips prices with not so cheap fine print.
Have had a few customers who come from there and tell me about it. Example;
Print is like half price... but...
1) file download fee (for receiving your email)
2) trimming fee (for cutting your job off the roll)
3) file preparation fee (if not 100% to spec) - and they'll usually still find an excuse even if you sent a proper file
There are also delivery fees, express service fees, and the list goes on. Not to mention there is also some fine print along the lines of *price applicable to orders of 10sqm or more. Orders under 10sqm charged at standard non discount rate bla bla.
Their product maybe isn't so bad, but because they appeal to the general public, they encourage them to buy from them, making them think it's "cheaper" to go direct. In my opinion they should at least limit themselves to only supplying sign installers or graphic designers at least, and not direct to the end user.
I'm sure similar ventures exist in the US?