probably can, but the main reason it will be forsale for that low, is because:
1) the buyer is too poor to keep it, or desperate to get the money for it - therefore probably didn't maintain it either, which may lead to potential headaches further on
2) it's already half stuffed, so by the time you put in a new motor it's not so cheap anymore.
Also when you factor in the insurance cost of around $1000 a year, petrol of about $50 a week, and everything else $8-9k is only the start. Anyhow, there are bargains out there, but there are also a lot of ongoing costs.