I'm looking for a 4" abrasive cutoff saw and finding that they are
pretty expensive for what they are.

I have this one. Probably the same that penn tool sells but you
can get options from the manufacture that are not available from
some of the resellers.

http://www.coasteltools.com/prod_ct3.htm

I like it a lot. A standard abrasive blade cuts small things
1/4 inch or less quickly. Bigger things are a bit slow.

I use a Dart DC motor speed controller and a
3 inch slitting saw to cut wood, brass and plastic.

My friend mike has the wilton. The wilton is better for thick
steel opjects. I was surprised to see how fast it cut a large
3/8 pin.

chuck