I would not pay more than $12-13 for each Quick & Casual voucher UNLESS you were going to use them at the counter service restaurants like Pepper Market or Beaches & Cream (if they're still one of the participating ones on the back). Then you have to factor in any shipping costs.
The Q&C vouchers are a good way to pre-pay for your meals, but there's no way I'd pay the prices they're going for on eBay now. Yeah, $20+ each - NOT! I think you can also buy them online at a ticket broker for about $16 each, but that's still high for most counter service restaurants.
We used them back in 2003 when I paid approx. $11.75 for each, and the DH and I usually split meals since we received a combo meal, dessert, drink (plus they covered tax & tip, too (if applicable for the restaurant). We *maybe* came out $2-3 ahead. I would not use them for breakfast since you can get a breakfast platter at most food courts for under $6, plus your drink.
I would check out the menus on
www.allearsnet.com and see what you might pick at some of the participating restaurants paying on your own (choosing a combo meal, dessert & drink). In most cases, you can eat way cheaper out of pocket than using the vouchers.