There's so many good folders in the $40 range. It may help if you could narrow it down for us with a desired blade length or other characteristic. I love my Subcom (carrying right now along with my Kershaw Baby Boa), but the blade is <2". Some suggestions made so far have blades ~3", others >3". I prefer to EDC blades in the 2"-2.75" range typically, except for weekends when I often have larger pockets. Overall size may play a bigger role in your decision than you think and you can narrow down your selections using size.
I have a spreadsheet I made of sub-$50 folders (many are <$40). I can send that to you if you'd like. It's sorted by either Brand or Blade Length (2 worksheets).
Instead of suggestion a specific model, I'd recommend you look into the following brands via their websites and stores (newgraham, knifecenter, etc.) to research price, lock type, size, aesthetics, etc.
- Benchmade (not many, but a few <$40)
- Spydero (a good amount <$40)
- Kershaw (several <$40)
- Camillus (the Cuda EDC is nice and slender)
- Buck (many <$40, Mantis is very slim and sleek)
- SOG (a few <$40)
The Subcom is readily available and a great knife. I also like the beefy look. The blade length works for most cutting tasks I need to do, but there are times I need a longer blade.