I'd bet we've all been there at one point or another.
The first show I ever went to I bought this
It was a whole dollar, which should give you an idea how long ago it was.(1978) At the time there were very few reprints and I hadn't heard of outright fakes. The place I hung out at let me know when I showed it to them. "It's fake, Wood isn't in the series of 120" darn.
I now know the cardstock is all wrong, the aging is very artificial, and even it wasn't fake it's trimmed. Why trim a fake? If you've got the equipment to print a fake surely you've got a papercutter too.........I've kept it as a reminder and as a curiosity. I've also never seen another or any similar ones that were as old.
Unless the money is enough to put you in a bind, (And if it is why are you spending that much on hobbies? ) The knowledge gained is usually worth more than you've lost. Buying the card above and finding out it was fake pushed me to buy the old sports collectors bible and the 1978 pre Beckett catalog/checklist book. It's been all downhill ever since
Steve B