The Mars hydro TSL2000 (300watts) on Mars hydro website is on sale for $199 right now. The TS1000 (150watts)is also on sale for $95 but you would need to double up and run two in your 2x4
Spider Farmer SF2000 (200watts) is on sale on spider farmer website for $219
The SF1000 (100watts) is also on sale for $95 and there is a SF1000D that DOES NOT have a dimmer (so you would have to raise it to change intensity) on sale for $70 - you would need to double up on these for a 2x4
I have an SF1000 and a TS1000. I like them both - I use the SF1000 in a small tent to start my closet grow then when the plants are big enough, they go into the closet and I move the SF1000 in there to hang along side the TS1000. When either one of them finally takes a ****, I will replace with a mars hydro because I prefer more watts.