In Spain, Marijuana is Legal, but selling it is illegal. There is a loophole in the law, there are many Associations, or growers clubs in most large cities. You join these clubs which are like a co-op, and instead of "buying" they call it donating to the operation. The prices vary depending on the club. The pictures are a club in Barcelona which is mainly for tourists, so the prices were the highest I had seen anywhere in Europe(15-25/gram). They did have a huge selection, and also a lot of concentrates.
The best prices I found in Barcelona at an Association were 6-10/gram. This was at a smaller club that was used more by locals than tourists.