The fourth most important basic handheld power tool every beginner should buy is a random orbital sander. While palm sanders are less expensive and can use plain sandpaper (cut into one-fourth sections), the random orbital version uses hook-and-loop fastened sanding disks, and doesn't sand in patterns, using instead a random sanding motion. This will motion will serve to reduce the chance that any sanding marks may appear on the stock due to the sanding. Of course, be certain that your local woodworking supplier has sanding disks readily available in a number of grits to fit the model that you choose, as the key to proper sanding is to use progressively finer grits as you sand to reduce or remove any marks that are left behind from the previous sanding.
Non-Standard Miter Slots - This one is a downer. One of the primary advantages of having a table saw is access to jigs that expand the saws functionality. This is a major issue if you plan on buying after market jigs. Given that we are limiting the cost of this buildout to $500, I am guessing that after market jigs are probably low on the priority list. Your going to want jigs once you start researching what they enable you to do, my advice is to build your own - there are plenty of plans online.
Ebates.com - Ebates is something I'll check after I've already found a deal that I'm going to bite on. The rewards aren't usually good enough to compel me to purchase on their own. But if you get an extra 3-5% cash back over your entire $250 budget, it can add up to an extra hand tool for doing nothing more than using their link to an online store.
The next important hand tool for the woodworker is an accurate tape measure. Get a retractable one that is at least 25 feet long. Any longer than that, and you start having problems getting it to roll back up. Since measurements on large scale projects can be very susceptible to even the most minute measurement variations, you’ll want to make sure the “hook” or tab at the end of the is firmly attached, with no give. When they get loose, you’ll have as much as 1/8” variation in your measurements. This can add up to some severe accuracy problems in the long run.