Everyone else was quicker on the ball (and more succinct). Here's my bloviating on the subject:
Call Tom Morris and at least one other "name" builder (edit: like the ones that Ty mentioned) of stunt planes with descriptions or pictures of the planes. Get prices. (Who builds planes? I dunno -- I don't pay attention, because I build my own!)
If Brian regularly flies in contests where he's awarded appearance points, and if he wants to be nasty, he should come up with his own price. Figure out how many hours it would take him to rebuild the planes, call local woodworking shops and see if they'll tell him their shop rates, then multiply the hours by the rate and add the cost of a kit to get an answer -- it'll probably be more than what the "pro" builders charge.
If it were me I'd be planning on replacing the planes by building, and I'd be able to justify it because I fly in events where appearance points are awarded. So I'd do the "build on my own" computation anyway, just to have an alternative proposal for when the insurance company tries to knock off $$. Sort of an "oh, you don't like my first price? Well, here's one that I certainly like better". It's always nice to have a zinger in your back pocket when you're dealing with insurance companies, in case they forget that their client is the one in the wrong.
Of course, if he's just going to buy replacements, then that simplifies things all around.
More edit: I hope that things work out. Some insurance companies seem to operate by being nice and paying out, others seem to feel that stinginess is the way to go, all the time. I hope the other driver's company is the former, not the latter.
And some unsolicited advise: Tell him not to sign anything about neck pain or lingering injuries unless he's absolutely sure that he's in the clear. Insurance companies are justifiably paranoid about getting suckered by professional ambulance-chasers about this, but on the other hand you can get smacked like that and have deep muscle, joint, or spinal injuries that don't show up for weeks.