As far as parts go the hardest things to find will be tinware - petrol tank, mudguards, oil tank, toolbox; that sort of thing. if this bike has all that you're probably not going to have much hassle. engine parts shouldnt be too hard to get, but you'll have to be open to the idea of looking overseas - including europe. i make this point because dealing with europe can sometimes be difficult if you dont speak-o the lingo
its a two-stroke so theres bugger all parts to wear out. crankshaft seals will probably need replacing, but they'll be proprietary parts available from bearing/seal shops. if you need maching work done that's easy, but sourcing oversize pistons/rings/bigend bearings could be a challenge (but by no means impossible). actually, having said that the crankshaft would be built-up with roller-bearing conrod big-ends. if this is the case the bigend bearings will be available from the aforementioned bearing shop
the price is not unreasonable if the bike is clean, straight and licensed. the latter is most important - its getting very difficult to license two-strokes in the current 'green-friendly' climate.
in my opinion jawas are strong reliable bikes, but theyre getting old and most have been uncared-for (or worse - bush-hacked). if you want to get enthusiastic about this bike and marque then i encourage you to by all means take the plunge and hopefully have some fun and learn a thing or two. realistically however, if all you need is a hack-bike to get you from a-to-b this isnt the bike for you. two-strokes (and again, only my opinion) are tricky beasts for the half-hearted.
at any rate, good luck!
Blue