Inexpensive High Voltage Power Supply
The Electronic Goldmine is selling a small ionizer unit that puts out 7.5 KV DC at a very small current. This is a safe and inexpensive way to get started with the static electricity experiments, since the unit only costs $10.95 in US dollars, and puts out so little current that you can safely touch its output terminal while it is running. (Disclaimer: I cannot absolutely guarantee that this is safe. Use this device at your own risk.) The Electronic Goldmine can be reached at 1-800-445-0697, or you can see the product on their web site at http://www.goldmine-elec-products.com/prodinfo.asp?number=G1783. The product number of the ionizer is G1783.
To hook up the ionizer unit, you need to splice it to a standard 110-volt power cord, since the unit only has two unprepared wires as its power input. (You might also want to add a fuse as well, just to be safe.) On the output side, the unit has only a single red wire connected to several needles for emitting ions. You can cut the needles off, since they just get in the way, and you probably don't want ions anyhow. The color of the output wire is somewhat misleading, since it is actually the negative output. The positive output is the white 110-VAC input wire. Beware! You might accidentally electrocute yourself on household AC if you use this wire as the positive terminal in your experiments! My advice is to simply use household ground as the positive terminal for this device, since that is were the white wire should eventually lead in a correctly wired home anyhow. See the diagram below. Have fun, and be safe!