I also use phpBay on WordPress sites. Good plugin. Again, I'd like to urge anyone aware of substantial evidence that any of the search engines, including Google, have gone on the warpath against BANS sites to speak up. The only thing I know is that there are sporadic complaints from some who've taken no steps to perform on-page optimization or SEM that they aren't seeing much in the way of organic traffic or even getting indexed. Little wonder.
Personally, I think that too much effort would be required to build the site to a level where you would earn decent money from it. That's just my thought, though. I don't use BANS, or PHPBay, but I do use something similar. I don't pretend to know how those scripts work, but I just use a cron job that calls a heavily customized SmartRSS plugin to do my ebay sites. I'm working on making them better too, for the end user and for SEO. With the long-tail keywords that the ebay titles inherently contain, I'm starting to rank really well in the serps, even though I'm not yet masking my ebay links. Maybe someday they'll do something, but I really haven't seen any issues either, at least with my sites.