Yeah, you get what you pay for. I bought the GTR Plans and I'm gonna build one from those plans. It's actually cheaper for me to buy the plans, buy the tubing, take a welding class, and buy the bicycle components. I did a priliminary budget and it would cost about $1,500 to build this thing. That including the the welding class. Without the welding class it would cost only about $1,000.
The other commercial version like Catrike and Wiz Wheel don't have the weight capacity I need. I weight 255lbs and will haul 60+ lbs of gear. Ians Sims suggested the proper thickness and diameter tubes to hold a 330lbs rider and 88 lbs of gear. That 418lbs limit! Only the Trimmuter and Scarab can do that. That's only because they ripped off Greenspeeds design!