For the Czech Republic? Yikes.
Let's see...
Well here's Play.com (UK) with payment in Euros:
Linkypoo. That's just for the expansion pack only, 60 Euros.. That seems expensive..! o.o;
Check this out though..
Same site, this time the 2007 Collection (with main game, RotZ, CoP and ToAU):
Linkypoo2. 21 Euros! But that's the official Play.com price and they're out of stock right now..
Notice though, in that same link there are two independant traders who have new, sealed copies of the 2007 collection. Selling for 37~Euros. Dispatched from the UK, but you could send an e-mail to them and work out the delivery charge for Mainland Europe no problem.
But yeah, I wouldn't bother with the stand-alone Treasures Expansion. Looks like it's very rare and is gonna cost way more than just the 2007 collection (which will work for you just fine).
Your local shop
should be able to get you a copy of the collection easily enough also. You should call them up and ask^^
Good luck.