If you're not hurting for cargo space, what's the harm? You sell them, great -- money for the next build. You don't, great -- parts for the next build . . .
. . . but better to have to sell/share than to not have then someone has to wait to go home before they can build/fly.
Personally I build/buy/fly planes I like and like the planes I build/buy/fly, but if I get "materials+" back from an airframe, *most* of the planes I'm bringing I'm holding lightly too. If someone makes a fair offer, I might have one less plane to carry home, and one more to build after I get back. (This being said, the only offers I've ever recieved were for my v-tail quad -- I fly my planes and generally, it shows).