I'm a newbie. This is what my project cost research has shown me.
42w bulbs in my area are around $10-14 each. For that price you can get two three packs of 26w bulbs from WalMart, three Ys from the hardware store, and have 156w. Even for 6500k, you can get a four pack of 23w bulbs at Lowes for around $10 or a two pack of 26w 6500k at WalMart for $8. Running all 23w/26w bulbs in Y splitters would also give you the ability to use one bulb of each spectrum per Y.