The battery itself is 71.13$, and they give you back 24.15$ if you return your old battery, so the net cost for the battery is 46.98$. But you have to factor in the cost of rental for the display heating machine, which is 49$ by itself. So in total, you're paying about 100$ for a battery replacement (+ the time you have to put in to actually change the battery), whereas paying in an Apple Store for battery service is 69$, all included (and with the peace of mind of not breaking something in your phone). So it's only worth it if you already own such heating device.
It's not likely that the pricing in Europe will be different