I dunno, 18 Euros seems like a big discount for not including a 9V battery.
The shipment of batteries/accumulators to the European Union is subject to various restrictions (hazardous materials), so this is probably the reason for such a big difference.
Apparently for this reason, they are currently buying versions without a battery from a manufacturer in Taiwan.
TME is an expensive place to buy Brymens - their BM829s is about 199 euros compared to 149 on the brymen.eu site.
It depends on the currency you want to pay in (in the Czech Republic it may look better as you don't pay for the conversion but pay in the local currency). It is also worth comparing shipping costs to another country. Of course, I am not saying that it is cheaper, but a person living in the Czech Republic can compare whether it is better to pay in CZK or in Euro).
I used to buy the equipment myself in Germany - because there was a lower VAT (19%), after the recent changes, regardless of where I buy in the EU (in online stores), I have to pay 23% VAT anyway, so buying locally it is cheaper (lower shipping costs, etc.). A person buying to the Czech Republic from Germany will also pay more (21% VAT).