The Four Pis are expensive to build for the average guy. I did alot of shopping around and found a few lower priced options.Here is one option that may work well for you......
Jammin Jerseys has 20 or so 2226H drivers that were used once or twice for $200 ea.
Also Parts Express severely lowered their Eminence prices so today
you can really save a bundle building your Four Pis.
$400 (2) 2226H drivers -Jammin Jerseys
$60 (2) H290 Horn Flares - Parts Express
$122 (2) PSD2002 drivers -Parts Express
$165 All crossover parts and two D-cup heavy duty binding posts from Madisound
$70 Shipping for all this stuff
$50 Build your own boxes with MDF and paint them.
$932 total
If you did'nt care about prices and just bought everything from Parts Express and had a cabinet builder do the cabs......
$1400 for Parts
$600 rough estimate for finished cabs
$2000 total