where to buy parts

I am on a mission to build a theremin. I have little experience with electronics or theremins but I have some worthy peers to give me a hand. I was thinking about contructing Art Harrison's Model 145 theremin from his web page. right now my biggest problem is finding all of these parts for a decent price. are there only online retailers that will cover most of these parts? also for anyone that has built this model, how much did it cost. thank you.

im currently building the 126 theremin and have ordered almost all of my parts from Digikey and from mouser. A few parts I needed to get straight from art "harrison instruments" and the usual quick run to radioshack...etc

I do believe this answers my question. Thanks!