Cheap all-time-low price tag games (according to SteamDB) that I‘ve played myself and can recommend:

Slime Rancher

Broforce

My Friend Pedro

Dust: An Elysian Tail

Poly Bridge 2 (also the first one)

Clustertruck

Risk of Rain (the old one)

The Swapper

Rogue Legacy

McPixel 3 (also the first one)

Overcooked (also the second one)

Party Hard

Trine 4: The Nightmare Prince (and other series entries)

Train Valley

Minit

All of these are of varying genres so probably most of them aren‘t everyone‘s cup of tea, but maybe one or two are gems that you hadn’t heard about yet. List isn‘t conclusive, obviously, but I don‘t wanna spam too much.