I went to the trouble of buying the hinges (and I had contacted Wedge-Loc directly because when I called dealers near me who were listed on their site I kept being told they--the individual dealers I called--didn't have the hinges). I finally called the folks at Wedge-Loc directly and they sent me to Kencove, since they stock all of the WL items.
After all that trouble and paying all that $$, when we built the round pen (for a clinic that was being held here) the slight slope of the area gave us trouble with getting the bracing system right and so we ended up sinking wood posts anyway and hanging the gate the "old fashioned" way. Now I have a set of t-post hinges that I don't need.
If you know someone who does electrical work, you can get coated aluminum wire. We used the coated wire to attach cattle panels to the t-posts and it worked great. I think it would be ideal for hanging a light gate from a t-post as well (we ended up using wire from a well pump, but it's basically the same sort of thing--just thick copper with coating).