If you're going to be using splitters and rigging up your own light fixtures, just make sure you heed your wattage ... Know what your fixture is rated for and make sure your bulbs don't exceed that! It's a serious fire hazard to overload a fixture and stuff it in a closet.
That said, most fixtures designed for use with incandescent bulbs will be just fine to use as pictured above, and you can make some great fixtures for cheap, as posted above ... Just check the numbers when you do to make sure the fixture wiring can handle what you want to do.
I'm a fan of the clip lights mentioned above, they are versatile and very handy. Whether you plan to use them to grow or not, I would recommend buying at least one. Very handy.
Craigslist is great too, just be careful.
Lots of options!