eBay with Rockwell Tools has the Rockwell RK9002 Jawhorse Sheetmaster for $200 with free shipping. Holds up to 48" sheets, folds down to a portable 43 pounds with straight-line wheels, and measures 39" x 39" x 334" standing. Tyler Tool has it for the same price.
43 lbs. isn't all that portable, but at least it's one-piece. Looks like it would tip easier, with the tri-point design.
I have had this for over a year, and it's a great. Easy to use, stable, and very portable. Cheaper at your local Lowes.