Is it legal to overcharge on shipping and undercharge the item?
you bet! its called fee avoidance and ebay takes it very seriously. there are others on this board that have had items cancelled by ebay for suspected high shipping rates (according to ebay anyways)...this board probably isn't a good place to think out loud about matters like that!!:-)
use the promotional .5 cent and .10 cent listing days to your fullest advantage to save fees...
i believe you're allowed to charge for handling and materials (if you're not already doing so), but overinflating shipping charges will get you in a bit of a sticky situation-both with buyers and ebay alike. (of course, i'm not talking a few bucks here, but really overblown shipping costs)...
unless you ship high volumes weekly, other companies will be just expensive to ship if not more, but if you ship in good volumes, there's fedex and ups that will give you discounted rates. there's alot written on the boards regarding other shipping companies...
good luck with your new ps status!:-)
Kat