It seems to me that their tyre prices go up and down based on supply (or not).
So seems like you copped a bargain their, when I had my Falkens all round, their prices were way up on £70, so I went to local dealer and ended up paying just over a ton a corner (fitting/balance/etc).
Maybe next time I'll check these guys out, but so far tyres wearing well, so hoping a while yet before needing to shell out.