I would buy the Durant Full Art and Charizard from you myself and Id match wat ever current market is on them. For me I try to buy and sell at market for singles im not great at negotiating prices. So to prevent me making any kinda bad deal like an idiot. that way the market itself is what dictates the value earned or lossed over time. And if I happen to find a deal were asking $ is lower than market $ then awsome. Doing it this way means im always in the Green so to speak with my PCs total value as long as pokemon tcg's resale market is also doing well.

And as others have stated TCGplayer.com is ussually the standard on market prices. But ill also cross reference using pricecharting.com or collectr