This is a single cutaway with one dogear P90, right? Assuming it's "real", all original and hasn't been refinished, it's worth what he's asking, maybe more, but nowhere near $10K. Haven't seen any '57s lately, but '58-60 double cutaway Jr's tend to go for $3000-3500 on eBay.
To be worth the $2900, or maybe some more:
1.) It doesn't matter if there is checking on finish or chips/nicks/buckle rash, but finish MUST be original. To the best of my knowledge these came ONLY in yellow to brown sunburst on front of body, brown on back of body/neck. If it's been refinished it's probably not worth more than half that.
2.) All parts should be original!!! If the original piece of shit wraparound bridge and funky tuners aren't installed, they should come with it or value goes down.
3.) Double check scale length, should be 24.75"; there were some 3/4 scale versions made, those are worth a lot less.
4.) Serial number should be on back of peghead, ink stamped in yellowish ink under top finish and should be "7" a space and 4 additional digits.
If typical vintage major repairs have been made, like broken off or split headstock reglued, or neck broken at body joint and repaired, it's worth a lot less.
