I bought a cheap 4K system off of amazon for about $40.  I had a project where I wanted to see what was happening but not able to see in "real time".  The recording did what I wanted.  Quality was par for a $40 setup.  Optics not very good. Hard to use. etc - but it worked for my project.

I have also recorded video using my cell phone and a dji Smartphone Stabilizer. I bought an older model OM4SE.  Works real nice but then ties up my phone.

An older model, refurbished or trade in purchased from a company that lets you return it would be what I would do to get a better quality system at a fair price.  A place like B&H Photo, National Camera exchange used to have used equipment, I have not looked in years.  I bought my refurbished/trade in Canon digital camera from National Camera exchange in Minneapolis years ago.