A little knowledge goes a long way
When buying a custom guitar, there are a few things it's wise to do. Firstly- how much do you know yourself about guitars? If it's not a lot, ask around your friends and see if you can get someone who knows a reasonable amount to come with you. You'll be a little bit more confident if you can get a second opinion, and they might spot things you miss. Secondly- have a good idea of what you want the guitar for. What kind of music will you be playing on it? What kind of sound do you want? Be sure you know the answers to these questions before you even start looking. Thirdly- how much can you afford to pay for a guitar? In general you'll get exactly what you pay for, but by looking for customized guitars it's sometimes possible to get a real bargain. Remember though, if it isn't what you want, it's not a bargain. Don't buy a guitar just because it's a deal! Fourth- ask as much as you can when you look at the guitar. What has been customized? How old is it? What's the origin of the different parts? The more you know about the guitar, the better. Apart from anything else it makes it easier for you to figure out if it is really a deal.