If you are going to do it, now is the time. I have only just come into the position of being able to realistically afford to lay out the cash to get one - I have loved them since I sat in a Chimaera at the NEC in the early 90s and values of decent ones are quite high and getting higher despite the doom and gloom. Properly decent cars are also getting rare as people are hanging onto them.
Other than chassis rust the only other thing to look for is electrical issues and general condition. Most mechanical issues can be easily sorted (other than steering as the racks are no longer available) but tatty cars cost the earth to retrim and repaint. Conversely, a top end engine rebuild is a couple of £k which seems good value to me. The rest of the parts are Ford and Vauxhall on the older cars so are easy to come by and most electrical bits can be found at Maplin.
Mine cost me just over £13k but is insured on an agreed value classic policy for £350 and servicing should be less than £1,000 per annum at my local specialist subject to nothing breaking.