hi i have been into beetles for years.
a grand should get you something solid and presentable, 500 a bit of a ratter. wher are you? my mate in sthingyhorpe is selling both of his at decent prices.
when looking at the car the first place to check is the heater channels (sills to most people). these carry heat fron the engine to the front of the car. warm air hits cold steel, condensates and causes rot! it is a big and/or expensive job to get done. do it on the cheap or badly any your door gaps will never be the same again!.
have a real good look at the front buklhead behind the pedals as that is a rust trap, as are the inner rear wings - have a good look under and behind the back seat.
engines - 1200 is very strong and reliable but slow. dont expect more than 70 (unless you can find a gt gearbox) 1300 are ok but a bit mor prone to oiverheating if not looked after properly. the 1500 is probably the best air cooled engine vw made.its not fast but is a happy cruiser and again, they are very strong. loads of bugsd now have 1600 motors and i have had a few and personally they are my favourites. again not fast but plenty strong enough. loads of performance parts to get the power up too without too much outlay.
put some thought into which model you want. the curved screen 1303's have a more modern macphereson strut set up at the front and independant rear and are a dream to drive. the torsion beam ones are a bit more hairy - the rear wheels arc up so tend to tuck under on really heavy cornering. that can be sorted though!
hope that helps