I picked up a conicle alum shade from the second hand shop for $1 which is sweet for my 105 watt cfl which is the biggest I can get here which wouldn't fit in a can anyway plus I wouldn't go for anything smaller now. I'm hoping to eventually have 3 plants under it.

If you go this way then make sure you drill some vent holes in the top of the shade cause the ballasts put out a little heat and need venting.