What do you mean "sell" your images? Do you mean to a publication? Or as files for someone to print their own 8x10s? Or as a collection of viewable images? Or as a royalty-free collection? Unless you are selling actual prints, using a simple system like Paypal is not a good idea. There are stock agencies that have very sophistcated websites that "license" (we don't sell images, we license them) images online, but they also require the user to fill out an extensive form explaining the usage, and that determines the fee, and then allows the download of a large file. I don't like that system because you lose control over your images, but again, its a very complicated system. If you're licensing your images to publications, you normally would get a check from them, they don't usually deal with credit cards. So again, what is it you want to sell?
And BTW, if you are at all concerned about your images being ripped off, don't make them available on CD. There is NO protection, except perhaps registering your copyrights (look in the archives for my comments on that) which is only after-the-fact protection.
Andy Pearlman Studio