Mike,
I buy many of my tools from
https://www.cpotools.com/bosch-recon...efault,sc.html
All of them reconditioned tools, and all have worked like new.
They sell a Factory Reconditioned Bosch 3725DEVS 5" ROS that rates very high on Amazon.com for $99 and a Factory Reconditioned ROS20VSC for $49.99. Here is the link to the factory reconditioned Bosch Sanders:
https://www.cpotools.com/bosch-recon...efault,sc.html
I have the Bosch ROS65VC with the 5" disk and like it very much. But its over your price range, even reconditioned. I recently bought the ROS20VSC ($49.99 reconditioned) because it is smaller and lighter, but have not yet had a chance to use it. Reviews say the ROS20VSC is slower, but there are times I'll trade speed for weight. Time will tell. The Bosch ROV20VSC actually rates just as high as the 3725DEVS on Amazon.
I'd suggest going with the ROS20VSC and spend the rest of the $$ on good sanding disks. I've read good things about Klinspor disks, but others can probably give better advice on specific brands of disks than me.
BTW, the ability to hook up a shop vac is an important feature for me, and the Bosch ROS's have that capability - they actually come with an adapter to connect to 1-1/4" & 1-1/2" hoses. The ROS20VSC looks like it has an odd-shaped connector, but its really just a round connector with a rectangular filter that traps very small particles.
Ken