Well, you all probably know by now that I do not hire a maid. In fact, I actually was a maid for a while, back when I first started college :)
It is extremely rare for me to buy cleaning supplies. I've found that baking soda and vinegar will clean almost anything, with the added bonus that they don't have the harsh chemicals that give my husband headaches.
I do usually buy some knock-off Comet, for when the tubs get really gross and the baking soda isn't cutting it, but the baking soda takes care of most jobs.
About five years ago, I took an old windex bottle, rinsed it out, filled it with 1 part vinegar to 4 parts water, and I've just been refilling it ever since. I use it to clean my kitchen/bathroom counters, floors, toilets, mirrors, etc. A couple of times a year I rent a rug-doctor to clean my floors, and instead of buying their expensive cleaner, I fill it with vinegar. It deoderizes really well.