speaking as an owner of 2 Wacom tablets. I would say they are definitely worth the price. I used to use one of the 4x6 Graphire 4 tablets and it served me very well for the two years I used it, now it's being put to good use by one of my friends who does a lot with photos. I have moved on to the 6x8 Intuos tablet. I love it beyond words. t has worked without a glitch in both Windows and now Mac.
For your price range I would look at either the Graphire series or maybe even a Bamboo. (the intuos models start at $250 for the 5x7)
Edit: If you are really used to just a regular pen in your hand I would also recommend adding a Classic pen to your list. all Wacom tablets come with a pen, but it's usually the grip pen that you might feel out of place using.
and here's a link to the
wacom site