It depends on what you're buying and why: Whatever you buy, verify the seal
I have a question, Recently I got some Topps (Series 1), and according to Bulbapedia, this Version would be the 5th Print (foils with a smooth finish but a black logo, features of both 1st and 2nd printings)
4 Olaf, Happy Passenger (Enchanted) - $78.66 Set Five, Shimmering Skies This card will most likely make you want to smile as soon as you see it
According to Hobbybin, Darkness Ablaze expansion's ultra-rare VMAX Charizard launched with prices over $600, though these have dropped to around $300 as time passes
It's less likely to appear in a trample matters deck with Tanglesap since that's a much smaller number of dorks and you are rarely running into multiple tramplers from your foes at once