Expanding on what John said, contextual descriptions of the images is the best way to go. As an example, you can take a look at other e-commerce sites. I picked a random product from thinkgeek.
Taking a look at the product images, you can get a good idea of how they approach alt text. They have "DIY Guitar Pick Punch Main Image", "Picks punched!", "Playing with a punched pick." and "Punching a pick.". They all describe the images in unique ways.
There are two main considerations. The first is making sure the alt text corresponds with the on-page content. In this example, "DIY Guitar Pick", "picks" and even "punching" match up with text in the page itself, such as the titles and the descriptions. Will this make or break the SEO of the page? Not really, however it does create a more unified presentation which results in a better SEO Optimized page.
The second consideration is simply to describe the images accurately. This is for accessibility. For users with screen readers, or even if the images don't load right, a good alt attribute will provide enough information to let the user know what they're missing.
Now, what you're physically able to do depends on your platform. Many solutions let you define alt attributes for each of the images, and you can configure them to pull those attributes when they generate and embed the image into the page. If it's not that robust, the solution will be a little trickier. If all else fails, just echo the product name into the alt attribute. It will be fairly redundant, but at least you'll meet xHTML standards.