For your budget, I recommend Tein Basic Dampers or a used set of the Super Street version. You will get a better ride quality over the Skunk2 and Omni. Tein USA provides support such as rebuilding.

Another option is a combination of Ground Control coilovers and Neuspeed/Koni SP3 shocks. You can add little things like the Ground Control tophats for 3/4 in more travel and Koni bumpstops to lessen the impact of bottoming out. A big plus is that you can change springs with different rates for street or track. You could get the tophats later if you need the extra travel, since the SP3 is already a shorten body shock, to keep yourself under budget.