Walgreens pharmacy has in-store Large Format Printers that produce signs now, so does Kinko's/FedEx.
Soon, WalMart will get machines that print signs.
I do thousands of $$$ worth of cutting jobs monthly out of a small Main Street shop that I rent, and purchase from several established local wholesale suppliers that deliver next-day (GRIMCO, FELLERS, HARBOR SUPPLY, etc.) as well as buying from places that ship to me at excellent prices (including US Cutter).
I compete with SIGNS-By-Tomorrow, FAST SIGNS, Sign-A-Rama, and many other places that offer sign-making to the public.
When I do a banner for $60, is that destroying the market? Hell, no, because banners can be had for that price online (See: Vista Print) -- what do you think, VistaPrint is a huge secret?
I offer my production skills, my time, my design abilities, and get all sorts of sign jobs every day from a variety of clients, at prices which are competitive and provide my clients with the feeling that they've been well-served.