i think the whole jail break thing is a no no especially when ur trying to sell it at a later date.
voids pretty much anything and everything to do with the phone, and trust me apple can tell, happened to my old 3G and they knew all right, they wouldnt even fix something that broke, due to faulty hardware because *it was jail broken*.
And i think your price should reflect this.
as for the $300 of apps, i MAY be wrong, but whenever i plug ur i phone into a unregistered computer it wont let u sync the apps of ur phone, and to add anything to ur phone ie music or apps you have, it completely wipes everything.
If u want to be more realistic with ur price, PM me. if not good luck.