need advice on what to buy

I want my second grow to be bigger and im not sure if i should buy 2 more 150 watt hps setups, or jjust buy one 400 way hps.the thing is, i already have a 150 watt hps setup that i think worked great and wanna keep using to get my moneys worth.
so im torn between either buying two more 150 watt setups(giving me a total of 450 watt) or buying one 400 watt and using only that....So i could either have 3 lower wattage lamps or 1 higher wattage lamp...what to do, what to do???

Also could some1 plz recommend a good fan that would suit my situation? Im basically turning my laundry room into my grow room, and i wanna get a good fan to hook up to where the dryer vent exhaust is suppose to go. The room is 8 feet tall, 8 feet wide,4 feet back. I kno absolutely nothing about inline fans. Do i need a 4" fan? 6in?10in?

Exhaust should be able to completely replace all the air in your growspace within 15 minutes. If your room is 8x8x4 you have 265 cubic feet of air. Venting your growspace completely every 5 minutes is preferable, keeps heat down, gives more breathy shit to the plants. A 50CFM fan will replace 250 cubic feet in 5 minutes. Overkill is decent, but not required.

Before I recommend lights, are you going to build a flower, veg and clone area? Or all the same room.

no comment on the lights, I have one 1k watter and like it. I will however comment on the fan question though. Your grow area is approx 256 cubic feet if you bought a 6 inch hydrofarm inline fan (154 cubic feet per minute I believe) it would refresh the air in your grow space once every two minutes or so. If your intention is to exhaust smell then you're just asking for johnny law to be flash banging your ass in the middle of the nite(very unpleasant). If you're exhausting for heat purposes theres still an odor problem. You should check out the do it yourself carbon scrubbers all over the net or consider buying a commercially made one( I made mine but then I work in a sheet metal shop). So in that case an inline fan won't really run a carbon canister well and requires a centrifugal or can fan. I bought a 4 inch hydrofarm can fan for 110 dollars myself and it runs my diy carbon scrubber well. I'm actually thinking I'm gonna try to use a 6 inch inline fan to run the smaller carbon scrubber I'm making now ( my big scrubber just recirculates in the sealed grow room because I use co2), since I find I'm needing exhaust when the temps get up which they have been. But for you if odor doesn't matter and you're exhausting for heat purposes then more than likely one of those 35 dollar inline fans at home depot would work. Anything 150 cfm will be fine. If you choose the carbon scrubber the 110 dollars for the hydrofarm can fan is well worth the price.
A little of my current grow... https://www.rollitup.org/members/dbkick-248527/albums/first-grow-12724/