When trying to cut back on the number of things you daily carry without getting rid of the essentials, it's key to find tools with multiple purposes. The Kershaw Shuffle series is one of the best examples of that on a strict budget. It's an extra slim folding knife with a 2.4" blade, but it also comes equipped with a reversible pocket clip, flathead driver, and a bottle opener.
Currently, the Kershaw Shuffle is on sale for just $8.75 or 34 percent off its usual price.
I sometimes carry the revised version of this knife, the Shuffle II with a tanto blade, when I don't want to carry a full multi-tool or such a large blade.
Update: 6/6/2018: The Kershaw Shuffle DIY, a "tricked-out" version of the knife with interchangeable driver bits is on sale for $16.35, just $0.21 over its lowest price ever.