Quoted from Damonator:But I think $5-7 would be a range to start with
I would agree with 5k as a good spot to start, but it really depends on the condition of the whole package.
PinLawyer sold his super nice restored BR with clearcoated pf for just shy of 7k. That to me is the very top end on this title in both condition and sale price.
https://pinside.com/pinball/forum/topic/for-sale-banzai-run-9#post-4173676
Aside from that BR prices are all over the board. 3500 can get you a solid working game. 4500 gets you a nice example without the typical wear/issues.
5-5500 seems like a good spot to be for a proto XR7 in good overall shape.