You didn't say what size blade you are wanting, so I'm assuming 3" to 4" CRKT uses AUS-6 and AUS-8 on most all of their knives. Nothing wrong with it. The AUS-6 is a little soft, but it sharpens really easy. I have found that it's very hard to tell the difference between AUS-8 and 440.
If you get a CRKT or Spyderco either one of those brands are going to be way better than a Colt or S&W knife.
You say you want a "bad-azz looking, quality tactical folder" Looks aren't everything. Sometimes the plane jane looking knives are the best performers. Also most "tactical folders" don't come with sheaths because they usually have a pocket clip. But there are a few that do come with sheaths.
I recently purchased a Spyderco Native with an S30V blade and I am very impressed with the S30V steel. It definitely holds an edge unlike anything else I have seen. This knife only cost me $56, so that's almost in your price range.
The main things I look for in a knife is quality steel and good ergonomics on the handle. You probably won't be able to cut as well with a knife that doesn't fit your hand.
The CRKT Cascade will probably fit your requirements best and it does come with a sheath
http://www.knivesplus.com/crkt-cascade-knife-cr-6914k.html
The CRKT Cruiser is similar, but does not have a sheath
http://www.knivesplus.com/crkt-cruiser-knife-cr-7914d.html
The CRKT M16 series is also very good, but I really don't like how they feel in my hand.
The CRKT Crawford/Kasper model is my primary EDC and I think it has one of the best handle designs on the market.
http://www.knivesplus.com/CR-6783-CRKT.HTML
The only thing is they only offer it in AUS-6 steel now. If you can find one of the now discontinued Professional models with the aluminum handles, those do offer AUS-8.
Try this place, they may still have some
http://www.1sks.com/store/crkt-kff-professional.html
I am a big fan of Spyderco as well, although I don't have as many of them as I do CRKTs. Spyderco does have higher grade steel in your price range where CRKT doesn't. But I don't know of any Spyderco folders that are offered with a sheath. One Stop Knife Shop has great prices and they are a great store to do business with.
http://www.1sks.com/store/spyderco-folding-clipits.html
Also the other links above at Knives Plus, I have bought many knives from them. Their prices are usually the lowest around.
I have found that normally you get what you pay for in knives, but to a point. The $500 knives usually aren't much better than the $150 knives. And for $40 to $150 you can usually get a really good knife.
Let us know what you end up buying.
--JT