If you want a utility knife, honestly, your typical $10-$20 home improvement store razor knife is not a bad option. If you're looking for a dedicated folder, Cold Steel has a few knives I would look into. Check out the Voyager models for some really excellent work knives, maybe scout around for a deal on a Code 4 in CTS-XHP (I've seen them around $65 with some regularity), or you might give the Cold Steel Tuff Lite a try.
Outside of Cold Steel (which can, admittedly, fall outside of the "easy to carry" category), check out the Kizer Vanguard models for good values on good knives. If you want something lightweight, the Spyderco Endura, Delica, and Native (FRN models) are all very good options if you're willing to swing a little higher on your budget (not knowing exactly what "medium level cost" entails for you).
If you're looking for something relatively inexpensive, then, the Spyderco Tenacious is a good option that can often be found for about $30. The Kershaw Skyline is right in there as well, and so is the Kershaw Leek. Some stores have a pretty solid deal on the Kershaw Injection, which, for about $15, is pretty hard to beat. I've also heard good things about the CRKT Pilar and Ontario RAT 1. Additionally, give Stedemon ZKC and Steel Will (Cutjack, Modus) knives a look.
So, having given a million options, here's what I would suggest in decreasing order of preference (and ignoring cost): Spyderco, Stedemon, Cold Steel, Steel Will, Kershaw, CRKT, and Ontario.
