Customs are okay, and can offer you a chance to provide some input into the type of blade-steel, grip materials, etc. However, many times the customs aren't made with the same tight tolerances of CRK or ZT, as has been already mentioned. Particular in a small shop, the custom guy may not have the availability of expensive machinery that is found in a larger facility, which allows for a much higher rate of manufacture with tighter tolerances. And...time is money.
Of course, you also have to be willing to last through the waiting period...and I'm not.
If you can't find something with ZT, Strider, CRK or Hinderer, you just are awfully hard to please. IMO.
If you have the money...and the time...there is some beautiful custom stuff out there...just not for me.
Sonnydaze