The Leek is on the very high side of cheap, at around $50. However, many of Kershaw's knives are priced very cheaply, and are excellent values. Spyderco Byrd knives and Benchmade Red Class knives are also value priced, though not as good as some of the Kerhsaws, in my opinion. Buck makes several excellently priced knives, including the venerable 110 Folding Hunter and the 119 fixed blade. A couple of Gerbers are decent for the money, especially the Gator- it's a little bit more expensive than the Buck 110, but if you need a knife that is light, or used for wet environments where the 110s wood scales might not be great, it's the way to go.
Ontario and KaBar both make some value priced traditional and mil spec fixed blades. KaBar also market the Becker line of knives, and the Dozier line of lock-back folders. Ontario makes foders, too, but I know nothing about them. Ontario also makes some very good traditional working knives, the most familiar of which is the Old Hickory line of traditional kitchen cutlery. Victorinox also makes excellent kitchen cutlery (called Forschner)
Victorinox also probably makes the best value-priced knives in the world, the Swiss Army knives. Wenger also make SAKs.
Many traditional knives offer great value, specifically the yellow-handled models from Case and Moore Maker. Americans aren't the only ones with traditional knives, though- Europe and Africa are full of them, including the Douk-Douk, Mercator K55, Opinel, Otter, and Okapi knives.
Finally, Mora of Sweden makes some very good fixed blades that range between $10-$30.