Good choice. my rule is CFL for veg and HPS for flower.
you can get a 250W HPS light, with reflector, hangers and digital ballast for around £120 (you could probably score one for £80 with just the basics if you look hard). its WELL worth the investment, digital ballasts are much safer than the ballasts on CFL lights (they wear out with age, can cause fires. just replace them every year..) and on top of that they are more efficient light wise.
CFL = 70~ Lu/W VS. HPS = 120~ Lu/W.
a 250W HPS gives out 30,000 Lumens, thats enough to flower 4 plants efficently (7500 Lumens/plant) a 250W CFL gives out 17,500 lumens, which is enough for 2 plants.....
On another note my 200watt cfl that died yesterday tripped my house out , the fuse in the extension lead it was plugged in did not blow and the fuse in the hanger also did not blow ,im assuming that this should also have a 3amp fuse in the hanger(it came prewired with a 13amp in it). As if its supposed to be a 3amp fuse i`ll change it before the new 200watt goes back in, thanks for your quick responses guys 