Superior results can be acheived through DIY if you let a professional design the crossover, OR, you invest in a bunch of testing equipment. Meniscus, as Mitch2 pointed out, is a good option. Better than Madisound, as Meniscus actually measures the drivers in the cabinet (or baffle) before they design the crossover. Madisound simply plugs in assumed measurements before they design the crossover.
It doesn't take as many tools as most would think to build DIY speakers. I've done 4 pairs myself, all mdf with veneer. There are more manufacturers than people realize that actually do grab off the shelf drivers and use them in their designs.
For reference, the scan speak revelator tweeter (9900) is actually about $200, the 7000 from scan speak is the one that is $400. The one that has me most intrigued is the 6600 that sells fro $220. With the air circ design, some say it's better than the top of the line 7000.
If you have not done a DIY speaker before and want to do a "no holds barred" version, my suggestion is to start small with a two way stand mount and see if you can get that right first. It's not as fun as trying a flagship, but you will learn tons before you spend all the money on the big drivers.
htguide.com/forum has a "mission possible" section that is all talk of DIY speakers. There are a few guys there that really know what is going on and can rival some of the best designers in the world when it comes to crossover design. Read some stuff over there, and you will be a step in the right direction.