From what I found on thezeb.com for the best prices:

ES-300 3-way crossover (99.95, cheapest 3-way crossover)
EF-6 Midbass woofer (98.95, shallower mounting depth appreciated would go in doors with 2.75" max mounting depth)
CL-4 Midrange woofer (58.95, only other listen 4" midrange was the ES which costs close to $200, would go in qlogic kicks)
TW-25SLP 1" Silk tweeter with image enhancement (59.95, I assume the tweeter is the same as the ones in their component sets? again would go in qlogic kicks)

And with thezeb.com's 5th Anniversary 15% off sale the total comes to: $269.82