I'd walk away...there's a reason you don't see many breeding size lesser females around. Unless the guy is getting entirely out of balls, I don't know why he'd let that one go, especially with the chance of hitting a $2,000+ clutch shortly down the road.
As for the asking price, $1,800 seems a bit high, but then again it appears to be a very nice snake. I think for lessers that size, $1,200-1,500 is not unreasonable though.
If you're set on getting a female ready to breed lesser, I'd find one from a reputable source...it'll carry a heavy price tag, but you breed what you buy.