Is There Any Way To Sell Really Old College Text Books?

Depends on how old the book is.  I would first try a book price comparison site, like compare-books.com, or many other ones, where multiple venues are searched to see if any are buying back the book.  The next option would be to search somewhere like Abebooks.com (rare and older books) or eBay to see if the edition you have is going for anything, and make your decision from there.  Chances are if it is not selling for much on either site, you are going to have a hard time selling it.  Textbooks generally drop in price significantly after a couple of years.