get a low mileage one, for that price you should be looking at at least a 52 reg, if you plan to modify it buy a car already done as they seem to go for pennies compared to the cost of the original car and the bits. They can be expensive to modify,partucularly the suspension and once you start theres always something else you'll need!
Oh, and dont buy a soft top one, theyre always worth less and the roofs are useless.
Gary