JP,

I have two ideas for you to consider. One would be to consider an active crossover (models from Rane, BSS, dBX, DEQX, Behringer, etc.) if you do not wish to develop your own crossover. Now this way will necessitate multiple amplification channels (for a three way crossover a six channel amp) and perhaps other considerations but it would do the job. This approach would be the science fair project in that you would need to work out the crossover for whatever choice of drivers that you might have. Plus some measurement capability would be needed to more easily deal with the crossover point and levels.

The second thought is to contact Rick Craig at Selah Audio (www.selahaudio.com) and ask him about his Linus 3 line array kit that uses the Dayton (Parts Express) RS drivers as the woofers. This kit is not shown on Rick's website but he does have a photo (linked) in his gallery. Rick uses, I believe, the RS150 woofer together with the Fountek Neo CD2.0 ribbon tweeters (that is a true ribbon driver) and he has worked out a passive crossover for this combo. I suspect that this parts kit may cost a little more than your budget ($2400 at last report) but it would be a significant step upward in performance vs. the other options you are considering.

Jim