How valuable or rare is this?

Thanks for posting! Knowing this era of collectibles, I'd say it's neither common nor rare. It might be worth a little more than what you paid for it. There are several other bobble-style figures and I believe this version was more widely available than others.

Wow! Does it really say "Darth Vader" on the stand? That's got to be worth something more, since it's clearly an error!

There's really no price guides for these kinds of things, but if I were selling an item like that on the secondary market I'd start with it's retail price, plus half. So if you bought it for 24.99, I'd start a bid at around 38 bucks.

Production errors and mis-packs are certainly rare, and to a completist collector it would certainly be an oddity that they may pay a little more for it. Just keep in mind that just because it is rare, it doesn't necessarily make it massively sought after. The Funko bobble heads are cool, but since they are not a limited edition item a rare variant isn't going to set the market on fire for quite some time.

Sharpy, great point about supply and demand.

Sadriel, yes, he is back in town! Picked off after some Facebook stalking, and pure coincidence, by yours truly. ;-)