No doubt pawn shops can be GREAT places to check for scanners. I can't even count how many scanners and receivers I've picked up at them.
Many people complain that pawn shops ask well over retail prices for scanners. You never pay asking prices at pawn shops... never! The whole purpose of shopping at pawn shops is to dicker. It's almost guaranteed that pawn shops have about 25% to 30% of their asking price invested in an item. That means they will heavily discount merely by asking. I've routinely bought pawn shop items priced $400+ for around $100 insisting that they quote me their absolute lowest price if I pay cash. Cash is king at pawn shops and gets you the best deals.
Now I'm not saying you can't be "burned" at pawn shops. Many folks will sell or pawn electronics when they develop small problems that they know will probably pass a pawn shop's inspection since the shop is clearly not an expert in the item... but performance is affected nonetheless. You really have to be familiar with the scanner you're considering and know how to fully test it before shelling out the cash. If the scanner just doesn't seem to work right... go with your gut feeling and walk away. There's lots of "problem" scanners in pawn shops, too.
It's absolutely not unusual to find digital scanners like the PRO-106 and PRO-197 for around $150 at pawn shops.