I was able to find Y splitters at my local lumber yard/hardware store, in with their light sockets and electrical outlets. They cost me a couple dollars each, but came with some excellent voltage/wattage ratings. (You'll want to check this if you plan to run large bulbs or multiple splitters.)
A lot of people will tell you that using a splitter off a splitter might not be a good idea. They are correct. It /might/ not be, depending on your household electric and some of the other bits you buy.
I picked up some 15 amp heavy duty lamp cord at Lowes for a few dollars and a heavy duty light socket (perhaps 8-10 dollars between the two) and wired my own lamp cord as well. (If you feel safe working with electricity you could at this point even wire a split in the cord and wire two of these sockets...once again, depends on your setup and comfort level).
Now...the advantages to this are nice.
-Fewer cords to plug in (Handy in older houses that sometimes only offer one per room)
-Each splitter/bulb added is adding to your overall light wattage
Let's say you decide to use 26w CFL's (the ones that say they are like a 100w incandescent) in the 6700 color range (Daylight) for vegging
Normally, with one lamp cord, that would be 26 watts, straight up.
With a single splitter, is it 52...add two splitters to that splitter and run 4 bulbs for a total of 104 watts. (The total invested would be roughly...35 dollars for 100 or so actual watts of CFL lighting)
Now, at Flower time, you can swap the bulbs to 42 watt versions in the 2700 (soft white) color range. The cool thing about this is that it once again effectively doubles your wattage...which a lot of people seem to stand behind for flowering. So...now, for an extra cost of 30 dollars or so for the different bulbs (They cost me around 8 at the local Walmart and similar stores), you have just converted your 104W veg light into a 208W flowering light.
(You can mix and match as well, though I suggest attempting to keep a balance of some sort. I've run a 42W 2700k opposite 2 x 26W 6700k before, and rotate them now and then)
Now...these will generate a little bit of heat. Nothing compared to a HID, but enough that you'd probably want to vent a stealth grow or small area with poor circulation. You can still keep one on these within a very short distance of your plants to maximize light intensity
I assume with this setup, some bit of the light is being wasted as one bulb shines on another...though, I'm not a light specialist so far all I know it could actually be a good thing. I prefer to err on the side of safety though and figure I'm getting a bit less.
(You may be able to find larger bulbs than those in your area. However, I don't suggest trying to mix the splitters with mogul bases...no particular reason Its just nothing I've ever tried and so I won't suggest it. I also recommend you pay attention to the impact any increases in bulb size could cause on the wattage being used and therefore the amperage through it all.)
Another option is to go to a place that sells bathroom or "vanity" style lighting (Lowes, Menards, Etc.) and you can usually find a setup that allows you to plug in 6-8 bulbs or so...be careful, because some are designed for low wattage bulbs. I know the one my wife has in our bathroom uses a half dozen 27 watt bulbs though and can burn your retinas out if you look up while brushing your teeth.)
