One of the first knives I got that wasn't a no name knife, swiss army knife, or that boy scout knife from cub scounts would be the Buck Approach. I'm not sure what made me like it so much at the time but I wanted it or the Revolution XT... And since the Approach was cheaper and I found a place that it was on sale at it went with it.
I've always been very happy with the knife. Of course I wouldn't recommend this knife if you're left handed, it's only openable with your right thumb. Though I also like that because I can shut it very easily with my right hand as well. I somewhat miss it when I use other knives and I try to shut them one handed. Though I don't have it clipped to anything, usually it just sits in my pocket. I really like this knife and I've carried it on me almost every day since I got it though.
As for your specs to it....
1. Maximum blade length 2 3/4" or shorter.
It's under this.. Not sure what it is but I know it's not 3".
2. Combination straight & serated blade.
Check.
3. Non metalic handle.
Yeah it kinda fails here, sorry heh. It was what came to my mind though.
4. Rugged & easily cleaned if dropped in salt water, mud, etc.
I don't know about any of it's resistance to the element. I've used it in cooking and for cutting almost anything I've ever needed cut. And I've never had any problems keeping it clean inside or out. I really like it.
Only complaint I've ever had was it's a bit stuff to open. I can't really flick it open. Of course I could loosen it but I never did. And now I actually like the feel of pulling it out.
As for price, I think it's around $50? I can't really remember, it's been a while.