I don't have a sweep and really never looked at one of theirs. Lots of people make low cost open sweeps and $1000 would be in the low cost category. A sheeted heavy duty sweep is way way more than that and much stronger. If you use a sweep, that is going to be one of the highest pressure points when working cattle.
Looking at pictures of their sweep, they are just one of their bow gates (one piece frame all around, top, sides, and bottom so the gate part does not sag) and short panels with the hinges welded on at an angle to form the curve of the sweep. Their pap cage is just made from 2 of their 26" walk through gates with some tubes welded on to space them out and some additional pieces in the right place to receive the handle piece to hold the doors open or closed.
Their products seem to be good value for the money. Galvanizing sometimes not the best in spots.