Bexar County caps small-claims at $10K, so that estimate is 73% of that. Doesn't leave much for legal representation (if used) and incidental expenses, let alone anguish and punitive remediation, if applicable.
What I wonder is this is if the judge would ask for multiple estimates and take the middle amount. I also wonder if the shop owner should offer to buy the truck if the OP's best-case scenario plays out. And by that, I don't mean after an adverse judgement the owner says "hey, about that truck-I'll give you the (say) fair-market value of $4K", but rather the "judgement price".
Say the truck is worth $4K. The new paint job won't add the $7,300.00 cost to the current value, but let's say it makes 10% of that above the value of a similar truck with decent paint. So, we're at ~$4,700.00 and the cumulative costs to the shop owner is his previous labor and materials (lol) and the judgement.
It makes sense for the shop owner to offer to buy the truck at the judgement price. OP ostensibly walks with a profit over fair-market value + the 10% bonus valuation over comparable trucks and gets another. Owner gets something to mitigate his deserved loss.
BTW, don't mistake this as sympathy for this ****** shop owner. I'm on OP's side and if it went down perfect, he could pay back some of the BS by refusing this scenario. It just seems smarter for the owner to throw that on the judge in event of loss.