Hey there are proberly more experienced peeps on here to give you a full guide, but from my experiences the price seems okay...(if in good nick)
Things to look out for...
Check service history (id only buy one, with full history) and when cambelt was changed (rec. at every 60k miles)
check for clutch 'judder'
any clunk and crunch noise whilst driving, common probs inc. ball joint, seized caliper pins,
also not sure if you have owned a lexus before, but they are thirsty for petrol