Hi
You say ‘ some are worth quite a bit ’ - how do you know that ? Locks are a highly specialised field, and as such some are, it is true worth quite large amounts. The majority though are not.
If you haven’t already I would advise getting a copy of the only serious price guide ever published, even though it’s years out of print copies can be found and it will provide a starting point for you.
http://www.amazon.com/gp/offer-listing/091463805X?tag=antilockcom-20&linkCode=sb1&camp=212353&creative=380553
If you purchase using the above link this site will get a small credit for the sale.
With such a guide then it’s up to you, ebay is a good venue, as are collectors sales (the latter are only a really good idea if you have lots of locks though), either way you will be forearmed with some knowledge about what you have.
It’s worth bearing in mind though that a number of factors can have a bearing on a locks value :
Does it have a key ?
Has it been taken apart ?
If no key - is the shackle frozen ?
These and other factors can adjust a locks value up (and down)
Good luck.