I also wanted to come up with my own design when i first started building DIY stuff. If you spend 5 minutes reading up on crossover design and some other related topics, you will have a clearer understanding why people on this forum will push you towards a proven design. I'm glad i've taken that route.
I built the Zaph center channel about a year ago. I use it in my main TV room and It sounds pretty good. It's a good value and comes with everything you need including an assembled crossover as i recall. Probably the easiest thing to get started in DIY with.
Recently i built the Tritrix kit. I haven't done direct side-by-side comparison but my impression is that the Tritrix sounds better than the Zaph 5.3... the vocals sound more natural to me and the design will tolerate laying it on its side to use as a center channel. You can order a Tritrix kit (comes as a Transmission Line kit) from Parts-Express and then build the Sealed or Ported variant (i built the Ported). The kit comes with components for 2 speakers and you only need one, but even still, it's only about $140. Good to have extra drivers for when your drill slips and you drill a hole through a surround. With this kit you need to assemble the crossover yourself - so you need to be able to solder and lay out some wires. You will also need to pick up some PVC pipe and foam padding if you go with the vented design.
To order the kit:
To see specs on the different build variations (transmission line, sealed, ported) :
I think the Triune design (http://speakerdesignworks.com/Dayton_MTM_CC_FIN.html
) linked to earlier in the thread is 4ohm, while the Tritrix is 8ohm, so i think you get more sensitivity out of the Triune as long as your receiver can handle it. But i haven't built the Triune so i can't comment on how it sounds.