Unopened pack of 1991 UpperDeck baseball cards (Foil Pack)?
831112
At most $1.  Open the pack and let your kids (if you have any)  use them in the spokes of their bike tires.
881726
Depends on if it's in good condition or not. And Topps cards weren't the greatest either, so it's hard to tell. Look it up somewhere on a sports card website.
955801
you could always visit the Beckett website at\n\nhttp://beckett.com
200347
Ebay is your best bet. Get a Beckett price guide and put em up for auction.
567531
Wow, I was expecting something more common when I opened this.  But what you are describing may be exceptionally rare.  What shape is the card in?  Are you sure that the card and the signature are authentic?\nBe wary of just going down to your local baseball card shop and trying to get a price for it, they might try to rip you off.  What you have could be worth a significant amount of money, and my guess is that it is probably rare enough, that the best way to establish a value would be via a well publicised auction.
214860
What card dude? I can probably give it to you but give me the brand and maybe even the number on the back. The # is probably in the top left corner, although it could be in the top right instead.\n\nUpdate** \nIt is worth around 5 bucks book value and only like a dollar on ebay.
672905
sorry those games are over you missed out   lol\n\nlook on e-bay or in papers for collectors
1059007
Beckett lists both sets at $40.00 (apiece).\n\nThis excludes the 70-card McGwire set, which books for $500.\n\nThe complete Christmas set, which has an extra card, books for $80.\n\nNo mention from Beckett about the worth of an unopened set.
875340
get on e-bay and see what they are going for??? \n\nme dads just sold a set of old civil war cards for a lot of dosh!!!!
292698
Get them appraised by a local card collector.  It is a matter of supply and demand.
376029
Divide them up into Team Lots and list them on eBay. Your late 80's cards are next to worthless and the only way you're going to be able to unload them is to mix them in with cards of more appeal; team lots is the best way to go.
996837
Listing has pictures\n10 - 1991 Pedro Martinez Upper Deck Rookie Cards\n $55.00\n\nI've seen some cards only worth one cent but this was the highest I saw. I don't know what card you have or the year or the quality but here is what I found.
622159
Go to a card collecting shop
216623
Unfortunately, due to the many companies that mass produced and mass marketed cards in the 80's and 90's, plus the fact that many collectors saved them and put the cards directly into plastic sleaves, there are not too many rare cards from that era. So I would have to say that you will probably not get much more than a buck or two for it.
816139
Yeah it all depends on the type of card it is and the condition it's in.  You can look in a beckett price guide though.  It's probably not worth much, I'd guess $1 or so, if that.
331849
Go to ebay,do a search on each card.Odds are someone is trying to sell same card,cards you have,This way you can see what they are really selling for.
1159365
Beckett.com or Tuff Stuff.com\nBut you will need to pay for it...  its cheap though