Are people really paying that much for HMR ammo? It's a £10 per box of 50 around here, and has been for years.
I had a Mach2 for a while but found it disappointing. I had some sub MOA groups with it but not consistently in the long run. I went back to HMR where the extra grunt was most welcome, but accuracy was the same.
In the very few places I could find it back in 2009 was paying £5 per box of Eley Mach2, and £9 for Hornady. I found that the Eley ammo was about 100fps faster over a chrono, and more consistent. I did however have a disconcerting rim split that blew the magazine to bits.
As Eley discontinued making Mach2 sometime before 2010, I'd stock up while you still can!