You have to be very careful buying a mezuza. It's not enough that it looks nice. A mezuza has to be written in order so if there is a mistake and the sofer doesn't notice it until later, everything from that point on has to be erased. I can imagine a scenario where two letters are slightly touching and a less than scrupulous sofer will simply scratch a drop of ink from between them. The mezuza will look great but is completely pasul and there is no way to know. You have to buy from a reputable sofer!!!