A little sandpaper or a bit of toe in usually stops the squeal. Clean the rims or even a little steel wool or fine sandpaper on 'em does wonders. Usually the squeal goes away after some use though. Sometimes the calipers get a little tweaked over time and if the pads aren't adjustable a little "tweaking" with a adjustable wrench will do the trick. I can lay hands on a quality vintage bike that needs lubrication and tlc for cheap that can give all the enjoyment I'll ever need. Turns out they made pretty nice bikes for the last 30 or 40 years.