Sparta Prague v Arsenal - Tickets???

A work mate of mine was just asking about getting tickets for
the upcoming Sparta Prague v Arsenal game

Can anyone recommend websites or anything for getting tickets
for European games like this?

I offered to bring him to Whitehall to watch Dublin City v Athlone Town
on Saturday but he kinda has his heart set on seeing Arsenal!

Tickets will go on sale to Silver Members on the 22nd of this month.
If they go on general sale they'll be available on TicketMaster.co.uk

I am trying to get to see that game.. but in the Sparta end I will be in Prague for a few days around then.