since you havent done it before, you will do well to start with a subwoofer or a 1way (full range driver)... if u have to go with a 4 way, go with a proven existing desgin, it wont be cheap for sure... designing a 4 way is a very complex exercise which i am pretty sure a newbie wont be able to get it right for a long time... if the plan is to just get some drivers, buy some crossover and slap them in a cabinet, the end product is most likely going to sound like crap.