:confused: I have 18 card collection of barry bonds cards. How can I get a value on them to sell?

I use eBay to check the value of collectibles. Find them for sale on eBay then put them on your watch list to see what they sell for. eBay also has a feature where you can check recent sales prices on them.

eBay is good for getting an idea of the current, possible monetary value of collectibles.

You also might want to take them to a collectible card shop for someone to see them "live" in order to determine a possible monetary value, because baseball card collectors can get really picky about the condition of cards as a determining factor to their possible monetary value.