Those prices seem pretty spot on to me, we have and do sell to dealer in Shropshire and Cheshire and they are the same.
We have also sold rabbits in the past, whole and frozen to a zoo in decent quantities for 80p each, not bad and less hastle than paunching the buggers.
I would say thats good price although i do not sell any birds or rabbit, the birds that are shot on a shoot day are shared amonst the guns & beaters if there is any left they go to friends & in the freezer, most of the rabbits i give to the local zoo they are more than happy to pick them up & some go