In general It depends a lot upon the quality of the individual stamps and if they have certs. That is if you are thinking traditional auction house. They will want to lot stamps that stand on their own as sound and well centered and certs for the better issues will get the greatest returns.
ebay on the other hand is an option if the quality is not very good and/or there are centering issues. Certs are not as common on
ebay either. The downside is that your realizations will be correspondingly low on
ebay. Really need to have a good feel of what you are looking at in order to render a more informed opinion.