urm, it depends where you are, if ur in the uk, for a 250w hps you can get the whole lot for around £80-90, ballast nd reflector and bulb.
but if ur in america then htgsupply is good, but you can get some great bargains on ebay if you spend a while looking.
as for the cfl comment duplex, i didnt mention anything about node spacing, i agree with you that cfls are amazing for the vegative stage, but theyre not great for flowering. true, it can be done, but for two plants, i do think a hps would give much better results, imho.