Seller wants to ship USPS priority ,1 to 3 day live plants but it appears OfferUp only ships first class. Can i arrainge my own shipping label? Or will OfferUp offer me a usps 1-3 day Priority shipping label? OfferUp seems to offier little choices for the seller who wants to do the right thing. It appears as if the blanket approach shipping options are created by folks who don't shop through postal services.