There have been quite a few folk asking about the elliptical chainrings for single speeds.
I organised a group buy a while ago from BETD goldtech and got a discount for the guys involved, but I don't supply the rings or have anything to do with the shop.
At the moment goldtec have a few rings left in 33, 34, 35 and 36t they're £49.99 a ring.
they're not shown on the website and your best bet is to give the shop a ring.
Just to clarify, I'm cock all to do with the shop and this in the nature of PSA for those that are interested/after a ring.
Oh and yes they're total snake oil, just like biopace and don't work at all (just to stall the usual STW bollards)