What you're describing is exactly what Chris Reeve aimed to do when he made the Yarborough and Pacific models. They are extremely resistant to corrosion in most atmospheres a traveler would face on this planet.
Those knives use S 35VN, and I really like that steel. You can also find it in some models Spartan Blades puts out, The Difensa and Harsey II.
Like others have mentioned, there are just a lot of options given your price range and what you're looking for. A lot of companies have tried to meet those needs. The knives others are mentioning are especially made for divers, who subject their knives to sea water daily. I don't think you need that much corrosion resistance, and would be very impressed with S35VN. Also, a maker named Bill Coye makes great tactical knives that are currently in high demand. The Ridgeback and Model 105. I would look at all these before making a decision.
Spartan Blades Difensa
Spartan Blades Harsey II
Coye Ridgeback
Coye Model 105
CRK Green Beret
CRK Pacific
These knives are generally compromises. You give a little here and give a little there to get the best all around performance. They retain some features that make them suitable for a combat tool, but they can handle pretty much everything - just not a good as a knife dedicated to each task.
Of course, there are cheaper alternatives
Look at the Fallikniven A1, Ka Bar's offerings, Ontario's combat type knives, etc. There are a ton of custom makers. Also, Knife Research, Fehrman and Busse may be a little closer to what you're looking for. Essee, Tops and Becker for more camp oriented tools that also retain combat effectiveness. Not to even mention folders - Strider, Zero Tolerance, Hinderer, Spyderco, and the list goes on.
Whatever you do, don't spend 300$ before looking at all these options. I highly suggest visiting a large knife store if possible and handling some for yourself.