I have no idea what 3 phase means, but you should just be able to buy a Dutch Barn reflector (about £15 brand new, so thats just less than $30) and the correct ballast (a 400w MH/HPS one), I think they retail at around £30/$55. Have a gander on eBay, I got a complete system - 600w HPS, reflector and ballast - for £65 including p+p!