I have seen it on various Online sites, like the one with my name in it. Depend on the size of the drive, but they come with various number of games.
To be honest, I and only looking for few games that is basically impossible to get today (Bloodbowl 2 as an example). The reviews on the sites is pretty positive, still it feels like it can be pirated games…
@Bob - I know for X360 emulation purposes with Xenia, you can "rip" your own games by simply installing them to an external thumb drive using the X360 and copying those files to your PC. Is this perhaps what they're offering? Just note you won't be able to play games installed to an HDD without a disc or it flagged as owned on your account - and that will be harder still with most online services for the X360 shut down now. I'd recommend just looking for second-hand games at this point.