If you are interested in the species and you think that’s a fair price then go see it and decide.
A quick MM search showed me 2 for sale at $200 so factor shipping you are at the price now.
If you are alarmed by the questions you pose then maybe find a solid breeder and buy one direct. You can get great deals from cl but also bad stuff so be careful.
Is she def housing them together? Where is the ten gallon coming from?
Some of the other stuff seem common especially for an uneducated or lax keeper. Sounds like it’s being fed wrong prey. Not handled a lot or well and these are things that can be fixed easily with some effort and patience.
It all comes down to you as a consumer and if you think it’s worth spending money on. You can get a pretty nice boa for $250 so take a look at the market and what catches your eye before you run and take on someone else’s problem or gold.
No mayer what. Excerise prioer qt especially when bringing in a random animal in.