I love a good budget knife. I have a ton of Kershaw's budget line, stuff like the Clash, Tremor, OSO Sweet, Link, and Thistle. For that matter, you can get American made models like the Leek, Scallion, and Chive for around $40. If you wanna try something with the Emerson wave, but don't want to or can't spend the bucks for an actual Emerson, the Kersaw Emerson collabs are available too, for around $35.
Spyderco's Byrd lineup has some good stuff, as does Ontario with their Rat and Utilitac lineups. The Utilitacs are especially noteworthy, they're very stout, well made, and run around $25...they're like a budget version of a ZT.
If you don't insist on "modern" features like pocket clips and such, you of course can go with a whole variety of Swiss Army Knives, the Svord Peasant/Mini Peasant, Opinels...
Honestly, once you're in the Delica price range, you're no longer in the "budget" category IMO, if you're willing to spend that much on a folder and call it a "budget" knife, you open up a lot of options, stuff like the Kershaw Blur, a lot of Cold Steel stuff...stuff most people aren't gonna typically think of as "budget" knives.