See, I've got loads and loads of merchandise. Expensive and otherwise. Literally I have to have spent thousands - tens of thousands! - of dollars on the stuff over the last 15+ years. But for the most part? I don't regret much of it. Most of it's cool, appreciated in value, and I didn't spend outrageously on. I've got the Master Replica phaser from FC. I paid $199 for it. If I want to? I can go on e-Bay and sell it for $500-800! Easy! Same for the eFX tricorder. I got a hold of a MR Klingon Disruptor artistic proof for a bargain of $179. Decided I didn't like it much; sold it 2 years after for $350! Now it's likely worth $1000 or more, but at the time I was just glad to make a profit off of it.
Those damn Nemesis posters/banner though... god they hurt. If I'd bought them for even $50 I'd still feel dumb. Because the movie just stunk and it tanked so bad! If it had been a good one, like "First Contact" I'd love them and I'm sure they'd be worth a fortune! But no, I bought junk from "Nemesis" that is truly worth more as the tree it was made from. That's the big regret for me. That they're so lame and worthless.
If I buy an expensive thing and I can re-sell it later? OK. Fine. I may never; but knowing I can softens the blow of wasting the money, lol.
And if I buy a cheap thing, an action figure or such, and I can't make my money back? Oh well, it was a cheap buy!
But to buy high and never recover that. Ugh. Of all my Trek collectibles, frankly, it's the big stand-out stinker. I've had other bad buys, but nothing so significant.
Once paid $50 for a model of the 1701-A with lights, already built. It was great! For 20 minutes. Put it in the back seat, my sister got in and threw her purse back there - wham! Smashed it to hell. Tried to fix it but I couldn't get the damn pylons to hold. I can blame my sister though for it.

The Nemesis junk I can only blame myself for.
WillsBabe I must say I'm shocked and dismayed by your throwing such things out. Why on earth not at least sell it on e-bay, even if you didn't get what you paid for it? $5 back from that $50 art item would still be something!
