Crossover design is the heart and soul of loudspeaker design. (Even with a single fullrange driver, the designer has to make sure the output from the various parts of the cone sums properly.)
Getting the right value crossover components in the right places comes first; boutique components will not compensate for inadequate crossover design.
Designing a crossover is easy. Designing a good one is not. It starts with good data and lots of it, and not many people have the equipment to generate their own good data.
So here is what I suggest: Either use a kit and build your own Wilson-esque enclosures, or buy your drivers from Madisound and pay them to do the crossover design for you. Parts Express is another source of crossover parts. Parts Connexion specialzes in boutique crossover parts... as you will discover, there really is no upper limit to the amount of money you can spend on crossover parts. But the best quality part in the wrong value is still the wrong part. The crossover design itself is what comes first.
Best of luck with your project.