thier responce isnt exaxtly helpfull, as you said, a light isnt in itself illegal, thousands of people use them for growing normal vegiatables etc.

maybe you will get better results shopping at a general "gardeners" hydro shop, rather than an outfit geared towards growing weed.

alternatively, you could try these guys based in the UK that i use, they are really helpfull and happy to chat about your particular needs, and they are savy enough not to ask any awkward questions if you know what i mean.

since your going to be spending a reasonable amount of money im sure they will sort somthing out with you, or at least point you in the right direction
http://www.aquaculture-hydroponics.co.uk/where.aspx