Dan,
I have a Porter Cable 7¼" model, but I rarely touch it anymore. My two go-to circular saws are the Festool, which is out of your budget, and the Ryobi 18v cordless I got as part of a kit years ago. It's only 5½" but it cuts just over 1½" deep, so I use it for construction projects around the yard all the time. I've even cut 4x4s by spinning the beam and starting the saw in the kerf from the previous cut.
Most of the major cordless tool manufacturers have a smaller circular saws available. With the right blade and a guide one could be great for breaking down sheet goods.
"Live like no one else, so later, you can LIVE LIKE NO ONE ELSE!"
- Dave Ramsey