DIY speakers can be a very successful avenue to go down. How ever, they do require knowledge of some of the whys one does something one way vs another.
Zaph's kits are definitely very well done and he "voices" them to be very neutral with passive crossovers. If this will be a first attempt, I would highly suggest a kit. You can get pointers on cabinet construction as this is where you will have the biggest impact on sound other than the crossover itself.
Active crossovers such as those used in WmAx's speakers yield excellent easily duplicated results. However they also require more amplifier channels thus driving up the cost.
