three-way towers

Wnichol, my favourite economy drivers are the Peerless range. Bang for buck I have not been able to beat them, (pricing may be different in your area). Unfortunately their 4" midrange seams to let them down a little, IMHO. You might want to listen to some other mids and pick something that you like, (I have a personal preference for dome mids, try them). Try Vifas as well, they're damn good for the price.
Another alternative is to audition speakers at your local HIFI store and clone something that appeals. I believe auditioning is an important step often forgotten in speaker building and can be half the fun.
If your budget is really restricted you may consider a 2-way speaker. In the past it was difficult to get drivers to cover the range and handle high power output, modern drivers are much better in these regards. Dollar for dollar 2-way speakers are often a better choice, (says him with a 4-way system:)).
Regards WALKER
 
:) im probably cheaper than you! but i do enjoy good sound at a cheap price. i used some of the CHEAPEST drivers i could find at parts express for my home theater and i couldnt be happier with the finished product! i do need to add some tweeters though. do your research, get some ideas and have fun! shallenn by the way, driver cost for my surrounds and center were under 30 bucks!!