There's a lot of 'how to buy' advice on this board and I'm sure Denise will show up with the link she keeps handy.
I'm more concerned about the offer itself.
Someone emailed you - someone you know or a response to an inquiry you made?
Let's assume it's not some random spammer. Is this a resort you are interested in owning? If you think maybe it is, have you determined how it will fit into your vacation plans? Do you expect to go there every year or trade it or what?
Do you know what the annual maintenance fee amount is? Have you verified that this unit is paid up on all fees? Have you done some reasonable research to satisfy yourself that there isn't a planned special assessment that the current owner is trying to avoid?
Since your registration here is brand new, I'd say SLOW DOWN if you weren't already in the market for a timeshare or if you were, but this one was not on the radar.
It could be a great purchase. It could be a disaster. Tread carefully, as timeshare isn't an easy thing to rid yourself of once you own it. Ask the seller why they are selling.
Also, what is the amount of closing costs and what exactly does that amount cover? There could be other fees outside of "closing."