For various reasons I need a throwaway for this but I can confirm I've ordered with United a few times and it has been smooth sailing each time. Their ModAlert is also genuine (compared packaging and job numbers over time and with other vendors) and remarkably cheap. Only prob I had once was they didn't accept my Visa card, but tried again with another and was OK.
It's worth noting that the "retail price" from the original pharmacy is stamped on the packaging. It's in Indian rupees, but it comes out to something like £1.50 per 10.. so they're still making a nice markup.