Thanks Arouse. I still like BobK's remark though, and I think he has a lot of knowledge and experience.
Without doing all the hard work required to make an honestly well-researched decision, I can see that if what Bob says is true (no doubt in my mind), my project would necessitate the manufacture of a circuit board carrying tens or more likely hundreds of led's.
Then, I could buy in a switching PSU I guess, but it would want to be a bit special because led's are current driven, not voltage driven. I'm already getting a guts-ache.
I've concluded that it's not worth the trouble it would take to build a homemade unit, and I'd rather have someone else responsible for maintenance anyway.
Thanks, guys. I needed to get to this point.