x3 just because it's cheap now doesn't mean it'llbe cheap to get up and running. Could need a set of tyres so that's £150ish. If it needs brakes sorting all round. I guess you would need to pay someone to swap your windscreens over unless you have the ability, then tax and MOTing it you're not far off buying one. And chances are once you swap the bits off your 1.3 and drive it about you won't want to go back to the 1.3, but will only have it in bits so won't get as much as if you sold it now. Combine the money from your sale and the money it would cost to get this one running you may have the funds to get a really nice one.
Buttttttttt if you're a tinkerer crack on! Don;t listen to what I said above - I bought a beetle that doesn't have an engine and needs a hella lot welding!
