I have experience with buying tires in Switzerland and Germany (Konstanz). As expected, the price level is generally lower in Germany, but IME prices vary wildly in both countries. Just make sure you call a few places on both sides of the border. A few calls can save you quite a bit.
Tire places often have a few preferred brands where they offer some good deals while they have totally inflated prices for other brands. Again, it's worth to call around.
In the past I found some excellent deals at
Pneu Bauriedl in Aadorf. They've been taken over by Vianor though, so I'm not sure if they're still as good.
I had a quick look at reifendirekt.de and it seems that for EUR 40 you get just some obscure asian "brand" tires. I would stay away from these. Tires are one of the few products where it's worth to pay for high quality brand name products.
If you want to replace just two tires I recommend that you stick with the brand and type that you already have. A car can behave quite nasty in a critical situation when driving with mixed tires.