Okay, clearly I'm going to need to provide background from the campaign.
The 4 very young white dragons were captured, rather than killed by the PC, a CG bard. She just didn't want to kill babies.
She had a long conversation with her followers. The pseudodragon argued for simply killing the very young white dragons, as "white dragons are little more than animals, unworthy of our heritage." Her librarian cleric argued for studying them under controlled circumstances, like a zoo or at his temple, which is in the tropics. The PC expressed the idea of training them to be good-aligned creatures. (She had nearly pulled this off with one goblin in the early phase of this campaign, so it's not a crazy thing to say.)
During the bitter cold trek back to civilization, the dragons showcased their chaotic evil personality, with petulance, backstabbing, straining on the leash etc. The runt even helped another white dragon escape, just to see what would happen. (It got caught.)
Recently, the player mentioned that she might trade some of the dragons. Potential buyers thus include: an ice dwarf merchant enclave, the Dragon Claw Viking clan, an ice elf clan that's LG-aligned, the temple to the knowledge god in the tropics, and possibly her own country's military (with the dragons serving as war mounts).
Basically, I need a best-guess GP price in my head so that I can adjudicate the horse-trading and bartering.
Again, the party level is 14th.