I been looking at this one can't comment on reliability tho but I think this one looks similar to professional ones.
Its about £ 60 - 70 ish with the accessories.
You can get them cheaper probably.
What you need is a good handle positioning as thats what lacks in the lower priced ones.
Probably tho they still do a great job.
This one here I'm interested in both the polishing and sanding action as my sander isn't really that great being none rotational.
And I have a drill attach but they ain't really upto much they do work well tho for budget.