You didn't mention what camera/model you are using. Unless you are using full frame Nikon (D3, D700), a 24mm is equivalent to 35mm and a 28mm is 42mm. Both are not much of a wide angle. Even if you're shooting FX, 24mm is still not quite wide enough.
I would recommend the 20mm f/2.8D AF. It is a good wide angle at a reasonable price. It is selling for about mid US$300 on eBay. If you're patient, you may find one at mid US$200.
You don't really lose money in good Nikon or Canon lenses. Just look at it as an investment. You will get most of your money back if and when you want to sell it. But in the meantime, you've got to play with some real nice glasses.
I am sure you can get a price from your local retailer.
But this thread is not about the camera, but the wide angle lens. The only reason I mentioned the D3 is that there is a 1.5x perspective conversion factor between Dx and Fx bodies.