I'll second the Byrd line. Even though they're made offshore, by all reports the quality is well beyond what the price range suggests and up to Spyderco's standards.

Another line to consider is the Buck Vantage series. These are US made, and come in three steels: the standard 420HC, Sandvik 13C26, and S30V. The S30V model (with G10 scales) can be found for under $50 online, while the 420HC goes for around $20. The blade shape seems well-suited for outdoors use. This will probably be my next folder.

Here's a link to Knifecenter , since they have info on the whole line. If you shop around you may find a little lower prices.

Cutlery Shoppe has the S30V model for $39.75. I hear their shipping is on the high side, though, so may pay to compare. Still, it may be the cheapest price for a good quality knife in S30V:

http://www.cutleryshoppe.com/index.asp?PageAction=VIEWPROD&ProdID=8688&HS=1