Just my two cents: I'd steer away from the M-9 bayonets, by whatever manufacturer: overpriced for what they are, and their blade geometry is such that they're truly hard to use for performing most cutting tasks. I got one once (by Lan-Cay) with an edge angle GREATER than 90 degrees.
I'd haunt eBay for Ka-bar (also spelling it "Kabar", because sellers sometimes omit the hypen); Ontario and Camillus have both made versions of the Ka-Bar USMC knife, and they all use the same kind of steel (1095, which is quite tough). Ka-Bar also has knives like their heavy Bowies and some of their camp-type large knives in 1085 steel--somewhat softer, less edge-retaining, but likely harder to break. Personally, if toughness is what you're after, I'd pick 1095 or 1085 steel over D-2, since I understand D-2 tends to be more brittle and more wear-resistant--which means it can be hard to sharpen (but also hard to dull). For an outdoors application, I'd rather have a blade that won't snap than one that won't get dull: dullness I can fix.
Other possibilities that might not break your bank: Ranger Knives (run a search in this forum) (the most expensive of those come in at around $110, I think); if something a little less straight-shaped and Western is of interest, you might also check out Himalayan Imports, which has a subforum on BF, and routinely sells hand-forged and extremely-tough Nepal-made khukuris; you can pick up one of these with a cosmetic blemish on the H.I. forum for $65 or so on a good day. Before doing that, though, look at Cliff Stamp's comparative reviews of Himalayan Imports products--nothing like reading about how those boomerang-shaped blades stood up to extreme abuse that snapped other makers' knives, to give you an appreciation.