Shameless self promotion: my Halfpipe plane should be scratch-buildable for $75 or less including a cheap transmitter expense if you don't already have one. I'm assuming you already have sufficient building tools:
https://forum.flitetest.com/index.php?threads/wingmill-rc-half-pipe-and-half-pipe-delta.66155/
As for storebought, I recently bought and reviewed a WL Toys F949. It's a model of the Cessna 182, rudder and elevator only like the FT Mini Scout. If you can find it for $50 or less, I totally recommend it. It's a light weight, low power model, so you won't be doing any aerobatics or flying in winds above 10mph, but it is a nice flyer for calm days.
Shameless self promotion again: