Long time tablet and Cintiq user here, ~20yrs tablets, ~8yrs Cintiqs.
From what little I can tell of your situation I would recommend just getting a replacement of the intuos 3 that you have. Since you don't like the intuos4 I would imagine that you would not be fond of the intuos5. If you are having surface scratch issues with your current one I would try taping a thick but smooth piece of paper over the top to revive the surface. You could similarly get a thin sheet of plastic. But if you go that route I would recommend getting the compressed felt replacement tips for the pen. Or, just get the surface sheet replacement, it's relatively cheap.
Intuos2's are still quite good (hardly different than the 3's) and they are much smaller and lighter, great for portability.
Aside from being out of your budget I wouldn't suggest getting a Cintiq. Tablets are perfect for students, wallet, portability, and many professionals (including myself) still use them and need to use them. If one day your career, workflow, preference is for a Cintiq I would wholeheartedly recommend it, it's a wonderful piece of kit.
Don't by the way get hung up on pressure levels, especially for a tablet. The lowest you are likely to get is 1,024 levels and very few ever had a problem with that. Same with start pressure at <10g, I sketch extreeeeeemly lightly and I have been able to get by with 10g on a Cintiq and can easily get by with 10g on a tablet (even though I prefer lighter).