Look at Omni's advertising...
"Hyperformance", "fastest Mac RAM available", "Apple Developer" "Certified Apple compatible" -- all of these catch phrases mean absolutely nothing about the quality of the RAM.
ALL compatible Mac RAM runs at EXACTLY the same speed in your machine. Because the Mac controls the memory buss, the RAM doesn't. My kid is an Apple developer. Apple does not certify RAM models or vendors. Speaking entirely for myself, and admitting that I have never bought from that company, I will say that I do not trust any vendor who makes vague and hyperbolic yet unprovable statements about their products,.
In the USA I like
Data Memory Systems . They have been in business more than 17 years, and I have dealt with them for over 5. They know Macs, they use Macs, they are honest and fair.
Thanks,
Trevor
CanadaRAM.com