I got the Peach Tree email too.
After going to their site I was surprised at how good a deal they are for a
pack of four. Does anyone know for certain that these are ball bearing wheels? I would hope they do if they support 220 lb. ea.
I don't know how they compare, but I bought similar looking wheels from Hartville Tool for $11
EACH for 3" fixed wheels and $17 for a 4" swivel caster wheel w/brake. The only difference I can see is that the 4" Hartville wheels are rated for 275 lbs. ea. and all sizes appear to have heavier frames and dust caps on the bearings.
I used Hartville wheels on all my shop-made mobile bases, and they work great. Unfortunately, Hartville has redone their website and doesn't have photos of these casters on it yet. Hartville used to give a WW forum discount to a few of the forums (Woodnet?).