Not exactly a “cheap knife” but I did score my first automatic knife as they’re apparently legal here in the USA. Has a 2 3/4” blade and made of D2 steel which seems to hold an edge well although this one could use sharpening. Thinking of buying one of those Ken Onion belt sharpeners. I’m betting a dagger could be a bit tricky.
I was just thinking back and I remember some folks in the past (not this thread) have mentioned a few brands that they considered "junk knives". A few brands come to mind that although they may not be as shiny and pretty as some more expensive knives, I never considered them junk. Camillus, Schrade, Ka-Bar and Queen all come to mind. Some guys will only consider the shiny Stainless Steel blades. I'm the opposite. I love the darkened (not rusted) and maybe even stained look of an old well taken care of Carbon Steel blade. I'd take that any day over a modern shiny S-Steel blade that's on almost all new knives of late.
I came across these years ago and bought one for under $10. It took a while to get here but when it did I was amazed at how sharp it was. They claim it's 440c and may well be. I've seen comparison tests of this steel to 8Cr13MoV and it outperformed it. I know it's a cheap and lightweight Chinese copy of a Spyderco, but for a "junk" knife, it was a good buy. But don't count on all the threads in the handle holding up if you want to move the clip around. Some didn't. I complained to the company and they sent me another and told me to just keep the old one.