I built my own similiar to the one Rovers North sells...
I used an 8" piece of 6" x 2" channel, a 14" piece of 1-1/2 x 1-1/2" x 1/8" angle and a receiver tube I bought from Northern for around $12.
I used my Bosch jigsaw to notch the channel and angle iron for the receiver tube, tacked it...