Try 2009 Beckett Annual Racing Price Guide #16 with Bonus Alphabetical Checklist. or there's a lot of price guide for you to look at, just look for pricing guide online. have fun.
You'll need to subscribe to the Beckett Non-Sports Cards Price Guide .
As a collector you should do what ever makes you happy. You could do both. open a few packs, and also put a box of unopened packs away. Depending on the set, and key cards from that set it could be a long time before the unopened packs are worth selling. I have a few unopened boxes of 1991 Donruss baseball cards. They might never be worth more than $10.-$15. Maybe in 50 Years they're be worth $20. (too many on the market, and no demand) Unopened packs from the 1950's for example sell for a lot of money because of the rarity of them, and the expensive cards that could be found inside. Depending on the set some of the newer cards could have future value unopened. There is nothing wrong with putting away some unopened packs for future value, if you don't get an itch and start opening them up yourself.
$5
it depends on the cards
Ebay.com
1 dollars
Yes. eBay is a source that many collector's use to get cards.
9cards
The diamond cards are part of the howrse 2011 christmas cards. They are extremely rare and hard to find. The collector cards allowed puzzles to be completed (allowing a new divine: Greyfell) and a player to obtain BM/shop items.
You can buy them online or from a collector
from toys'r us
It is worth $240