Oh sweet, thanks!  It looks like this one has Paypal processing included, or at least a free plugin.  OpenCart has plugins but they are pretty pricey! 

Are you both on Storage Hunters/Wars??! If not, why not?!

Not such a bad idea driving people from ebay to her own store but unless the price was lower (though I'm not sure you could compare since you're selling 2nd hand stuff) I'd still go through ebay for the safety/feedback aspect.

Can't really help on the software, except to say I'd tend to agree with Ant, it'd be likely people will prefer a name they know. Have you looked at Etsy? Might also be worth getting involved in, probably as an additional thing rather than what you're looking at now to replace the other.