I called both Tweety's and Mor/ryde. Tweety's wanted $139 + free shipping. Mor/ryde want 168 + shipping. Both were the price for one brace, not three. Makes building your own for less than $50 sound better and better.
I think I will use a 5' length of 3" OD .25 wall and 1" length of 2.5 OD .25 wall, one sliding inside the other and bolt through with a couple of 1/2" #8 hardened bolts. I will weld that to .25 flange plate.