This is a risk of getting estimates via text message but, reading that exchange, I'm inclined to give the guy the benefit of the doubt. Here's why:
Right around 640
This is a ballpark figure because he says "around 640."
If you were to get it, 650
He's narrowed it down to a specific price and it's still around $640. I could see, however, how it could be misconstrued with "you" implying a different price from "not you." Text message...
720 + tax installed? Plus powder coat if needed
Now the price is the $650 with an additional $70 for installation which equals $720 (excluding tax in all cases).
Not sure if it is powder coated.
So he doesn't recall if the item comes powder coated at the $640 price point. He says he'll follow up and confirm an exact price for the item tomorrow, including whether it's the powder coated variety. It also sounds like the price on the written estimate (which would have avoided some misunderstanding here) could come in lower than what he's suggesting here.
Seems like the problem is he makes a harmless joke about your lucrative (or not, doesn't matter) line of work mixed in among your ballpark estimates, and all over text message without any other social cues.
I could be in the minority but I don't see any malicious intent here. YMMV.