You have to spend money to make money (as the cliche goes). Honestly, if you think your idea has some merit, and could potentially make you a good chunk of change, then the patent is worth it. If you think the idea is a good one, but not worth plunking the money and time down for a patent, just go ahead and build it. Sell it to your friends, sell it to people on the X and PWCtoday. If it keeps up, use that money to patent the idea then. Look into what it would take to have a "patent pending" on the design, might be easier than you think. If nothing else, instead of mailing the design to yourself, take it to a notary and have them notarize and date it. It is a better method of at least dating the idea, if down the road you did have a patent and needed to defend it.