Tricky choices - from experience I'd say that it's a good idea to have a general purpose scope.  Your budget will restrict you to something fairly simple - or a lucky second-hand purchase.  For the Moon and planets you can get away with a scope of modest size on a fairly basic mounting. At high resolutions the blurring effect of the atmosphere dominates which means that the actual performance of larger apertures compared with their theoretical performance is usually disappointing (unless you are