High Pressure Sodium bulbs are fairly cheap for a 70w or 100w which (I hope) would be enough for one plant, they are only a few pounds, however the rest isn't so cheap, I think I need a ballast which seem quite a bit but what else would I need and how could i get it all to come out of a UK wall socket, or would it be cheaper to use a car battery or something recharge it when it needs to because i see lots of car HID stuff on ebay. Basically I just want the best light for very very cheap for one plant, I also want as effecient bulbs as possibe.Could someone tell me the cheapest way? Thanks
Look for used equipment in local hydro stores or used sites (craigslist or similar sites in your area). Depending on the size of your space, you might want to go with something a bit bigger, like 400W. 100W is pretty small, and they might not be much different in price.
Auto headlamp HIDs are Xenon. As long as they're in the right spectrum, I don't see why not, but you'd need a bunch. They only put out like 2,000lm at 30w each.. They're also not as cheap as HPS and MH and you would need to drop probably $200 on a constant 12v power supply to drive the Xenons. Without an alternator, they would drain a car battery in a matter of probably 60 minutes or less (When the engine is running, the alternator charges the battery and powers all electronics). Or is that not what you were asking about with the car HID stuff?