Do It Yourself Speakers

Diy is the way to go for high performance speakers -- unless your bank account is superlative!
I strongly second Slaufer's recommendation for the Orions. This is a VERY complicated and elaborate design; easily amongst the best sounding dynamic speakers commercially available -- if not the best (and I've listened to many -- OK, not all:)).

Also, very strongly recommend CLueless' visiting list; I would add and also recommend you visit JPO's site and look up the Point 75 project -- another good design by Troels Gravesen that has a dipole midrange.
Good luck!

Putting together someone else's design in kit form is not really "speaker Building" in the classic sense. Don't get me wrong: I think these kits are fine, and I use them myself, but it isn't the real thing.

After building a run of nice two-ways in the early 90s I decided to build a three-way of higher performance. After LOTS of work I had ONE mono prototype (8" Peerless +5+0.75" SEAS) voiced really well. After learning that subtle crossover value shifts that I found important measured only 1/3 dB over an octave and a half in the upper mids, and that I could NEVER affordably buy driver pairs that well matched I gave up! Driver manufacturers often custom-match runs or pairs for $$$ to high end speaker producers, as getting cloned response in the midrange and treble is critical. Snell helped pioneer tight driver response QA, and I imagine the Brits too, back in the LS3/5 days for the BBC. After listening to the staging ablity of stereo pairs where the manufacturer matches and catalogs all drivers to a 0.5dB window (my Parsifal Encores, for example), I'm pretty sure I'll never reenter the arena. Even Boston Acoustics uses reasonably-sophisticated QA for its own tweeter production. As driver manufacturers routinely sell off the "outliers" for the DIY market, getting a matched pair of ANYTHING becomes very tough. The 2-3dB sens envelope spec'ed by a tweeter manufacturer can be 5-10 just-noticeable-differences in crossover-tweaking in the lower treble. Too much work to make matched pairs for the little guy...or at least ME!

By all means checkout Linkwitz Labs! Easy to build, unconventional looks, superb sound. I have built the Plutos, LXminis, and the LX521-4 (open baffel). No better sound for the $$. You can use other subwoofer sections with the LX521s as the "real ones" are pricy. Madisound has kits with packaged electronic crossovers. Contact me for more info if you like.

Holy zombie-thread, Batman!