Pittsburgh Wholesale, near the Pizza Pizza, has a decent selection and price, although the prices aren't as great as they used to be.
Grizzly Sports Cards has a crazy selection, but are a touch pricey.
Martin Sports will have plenty of vintage.
What I do each year is commit one whole tour of the show to wax pricing.
Grizzly is top tier, Pittsburgh low tier. Note their prices, and then tour through the "little guys". Allstarsports, Len (big tall, bald guy), and many others will have little surprises along the way. In the spring, the best price on 06-07 SPA was aguy who was carrying almost all singles, and about four different brands of wax!!
Good luck, and keep your eyes open!!
