Hi Seba. Haven't heard from you for ages mate send me a PM be good to catch up.
Regarding your pod build, if I made one it would probably be around the same price as the whifbitz if not a bit more as it will need smoothing and spraying so I think thats an awesome price.
I want to do a comparison to help you solve your issue.
The whifbitz pods are located as far down the pillar as you would want to take them. This gives you maximum headroom. The dual pillar pods that are sold on ebay have the two pods on the pillar higher, and are evenly spaced. This brings the pods closer to your face, and further away from the pillar. The only example I can give you of this, is the grey pod holder. I can't find any other pictures on the forum or google search (only had a quick look).
My advice, is if you really want a triple pod, get some dimensions from the dual whifbitz pod holder, and work out if you can add another pod to it, then cut a hole for wires and fibreglass it to the pillar, smooth it, and you have a seriously stronger triple pillar pod, the third highest pod being the only custom peice required.
Easy!
http://whifbitzperformancetuning.co.uk/images/fibrepillarpod2.jpg
http://www.fqperformance.com/shop/images/evo4-660mmtwinpod.jpg
This image shows how the pods are located higher up the pillar. On the supra, it is not as long, therefore you would not have the room for a third pod. The whifbitz pods are lower down the pillar.