The early woodworker get the tool. After reading about woodworking machines here, and looking at pictures, you eventually are able to look at a used machine and realize if it is worth having.
I bought a used Rockwell 13" planer at a yard sale for $100. I knew nothing about this model, but could tell it was well built. No plastic parts was a clue! It ran and sounded good. Just a bit of rust. Cleaned it up, adjusted it, and it cuts great with no snipe.
When buying any bs, be sure to check the guide assembly, and the table trunions. Both fairly fragile parts, that can get destroyed in moving a saw.
If you see an ad for something you are interested in, call asap, and tell the seller you want to buy it, and arrange a time to pick it up. I always tell the seller I am coming quite a distance, (even if it's 20 miles away) and just want to be sure it will not be shown or sold before I get there. Been there. Done that.
Then in the time you have before picking it up, research it if you have to. I like to go and pick up asap. Some people can't resist a higher offer.