>>983876>spending £100 just to bin itShameful.
Jokes aside, just get yourself a stainless Mora Companion and a good hatchet/axe. This is probably the best course of action here.
If you /must/ have a big knife, you should forget about your stainless requirement. Good stainless steels will run the price up. Just get a high carbon steel knife and oil it up.
You can also meet in the middle with D2 steel. D2 isn't a true stainless steel, but it has a lot of Chromium in its composition so it's not going to rust as quickly as 1095 and the like.
Cold Steel sells the Leatherneck in D2 for around $70 USD. Real Steel also sells a bushcraft knife for around $60 USD, although it's a smaller blade (4" or 10.16cm cutting edge).
Finally, maybe check out Steel Will. They use a lot of stainless stuff, and even have D2 and Bohler K110 (D2 equivalent I think) knives.