Hello Ken,
Bit of a question this. T5 is fairly new is more expensive and long term reliability? will you ever get your money back? Metal Halide units are alot cheaper but lamps (bulbs) are not cheap but are getting cheaper. Reliability has got much better, I fitted some of these units a few years ago and they failed early compared to other units in building, but the ones fitted sinse are still O.K. (Hey the lights have gone out). If I was you I would try your local Electrical factors and if they are any good they should do a site visit, and let you know how many fitting you will need for correct light (lux) and running costs etc. (I Have the miss fortune of being a qualified electrician. Don't ask. When did it all go wrong).but without getting all PC please be aware of any regs you may have to observe if doing it yourself.

Regards,

Ian.

Its Not Easy!!!!!