I think it's a fine price...nothing that raises any flags...pretty much par as far as prices go, IMO. It's not like a $1,000 snake being sold for $300-that would raise flags immediately. You always take chances when buying an animal. Probably more so when buying off CL ads. If you check them out, all is well, then go for it if you want them. Again, it depends on the quality of the snakes, their eating habits, weight/size/age, etc...
As far as keeping records goes, I am all for it, but this could very well be a person's only 2 snakes that they realized they no longer wish to keep. They could be perfectly taken care of without any records being kept. I, for one, could easily manage a few snakes with no record keeping at all. I'm just playing a little devil's advocate here, but lack of record keeping does not equal lack of care.