Five thousand miles, or 105,000 miles? They've only got five-digit odometers, as far as I recall, so it's worth bearing that possibility in mind. My gut instinct would tell me it's the latter, but stranger things have happened.
At any rate, I wouldn't want to pay more than a grand or two, if that (based on not knowing anything about it, mind). You can still buy a running 924S for about £3500 – and it wouldn't take long to chew through £2500 if you were putting the entirely unknown car back onto the road, if not more.
It really depends on what you want to do with it, how much it needs and how much you're interested in working on it and doing things yourself. Do you just want a 924S you can hack about in and don't care what kind of condition it's in? Then it could be an option, if you have the space, tools, time and inclination to work on it.
Do you just want a smart car that's easily enjoyed? Well, an immaculate 924S only costs about seven grand – and if your project needs paint and bodywork, you could quickly get up to that level as well. That's particularly true if you're going to farm a lot of the work out.
If you just wanted a 924S to drive and tinker with, I'd recommend just skipping the aggro and buying a known going quantity. It'll end up costing you less, financially and in terms of time and grief.