I think both Mattail and Rax2133 have given you very good advice, but I have a couple of additional points to make. Giving the ebay page a good "look-see", and with the help of google, it appears that the product you are evaluating is "Shop Creator 4.0" by etoshop.com.
The more I look into it, the more I'm suspecting that a "dissatisfied user" is trying to "unload" his/her copy, or that the publisher is trying to "dump" their "dog" to unsuspecting ebayers.
A careful review of the information about their program on their site has a few indicators that I would take as cautions:
1) The product is an "offline" website creation tool that, even though in one place they claim "runs on linux or windows", is clearly a windows application. There is also contradictory information regarding the webserver requirement right on the site.
2) Checking the faqs regarding the program reveals only explanations of windows runtime errors. Note that under "Support" on their website they state:
Windows 95/NT/98 to run the creator program
3MB space or more
RUN IN PC: Personal Web Server to test run the store from your computer
RUN IN WEBSITE: Windows NT Server hosting website with Access database and ASP enabled
3MB web space or more"
AND while the site has the text "Online Manuals", there are no manuals actually lined from the site, and there does not appear to be any kind of a support community or forum.
3) The Demo offered is an .ASP application that will not run on Dreamhost, or other linux server that is not running some .ASP environment emulator/converter (such as the one by Chilisoft).
4) There is no clear picture of what the product will produce - it appears that, at best, you will get some "pre-generated" .html or .asp?) pages to upload to your "webspace" and the use of an "SSl form" to submit payment to PayPal.
5) Actually, there are a lot of other indicators that you probably would be better off with a different solution. Even it it was "free" (which according to the price it ended at on ebay, it pretty much was!), I wouldn't invest the time trying to get it to work on Dreamhost (it probably won't) or trying to build a ecommerce site" that way, given the "free" high-quality alternatives.
There are numerous "free as in free beer" open-source alternatives, with more features and more standardized technology. Dreamhost's own "one-click" install of Zen Cart would be a far better option, and you might want to look at virtuemart, which is a high-powered and easy-to-use component for Joomla, another one of Dreamhost's "one-click" installs.
I'll guarantee you that you will not save any time or learning curve with the product you are evaluating. My advice is to save your money, and (more importantly) your sanity, by trying one of the mentioned "open" solutions before spending anything at all for something as poorly described and primative looking as "Shop Creator 4.0".
You are also much more likely to find useful help, both here and in the open source community, for the programs I and the others have described than you are likely to get from "etoshop".