Well here's my 2 cents (from my personal experience)

If you do it yourself, invest in a BIG, quality Baldor buffer and the big wheels and the compound kit (TP Tools have a great package deal). Small, cheap Harbour Freight buffers and wheels just aren't up to the task.

Don't expect great results in a short timeframe. After you hit the first piece you're going to see a million scratches you didn't notice before. Each one has to be SANDED out with multiple grits before its ready to be buffed.

Dents are a whole other issue.

In the end you will have either:
a) spent half your life buffing the stuff
or
b) wish you'd left well enough alone

Regardless, you'll have spent a bundle on tools and you will have a clear understanding why the guys who do it charge so much.