Superficially, the I-Match appears to be identical to the Northern Tool, Harbor Freight, Speeco, Cat-1 3-point Quick-Hitch (quality may vary widely) that has been painted green. I have no idea who came out with the original design.
Harbor Freight's is cheapest by far at $99. Harbor Freight has two variants on their website. One is listed as having 26 1/2" inside spacing and the other with 27 1/2" spacing. I got the former because it was on sale for $69 and wasn't paying attention. I had to modify (8 lb sledge and metal cutting wheel) to to get it to work with my Woods box scraper. Pretty much everyone else that has reported on the HF hitch has said they needed to make the same mods. I believe that even with the 27 1/2 spacing some mods are necessary. I also needed to order a flexible hitch adapter for top pin bracket from HF at an additional $15 delivered (SKU 29309 which is not listed on their website) because the top hook wouldn't work with either of my 3-point implements. I haven't received this yet, so I'm not 100% sure that what I ordered is what is listed in the manual, since the name in the manual doesn't match the name given by the rep on the phone. Anyone with decent welding skills could fab one easily.
Pat's Easy Change System is much more flexible, since it just modifies the lower arms.