Quiks66 is the username of the member on here who sells the Odd Coupe clipons.
Vortex is not an unknown brand. They make very high quality products. Though, their clipons are just not too well known and popular among the 250 crowd.
http://www.vortexracing.com/
Haven't heard of Pro-Tek.
You can't go wrong with Woodcraft though as they have been proven to work.