A few decent cheapies on the eshop.
Conduct Together has an 80 on Metacritic. Has been 1c on the US eShop recently, but for those without the luxury of access to said store, this is the cheapest it has been locally.
Goonya Fighters has been in sale more than not since its release, but for the price you can do a lot worse
Found this but not bothered posting - Celeste US$6.79 (~A$9.79) @ Target US (digital download).