Great idea Kelly. There is definitely a market for this service. Just make sure you have a few different sizes choices, and always put a condom on it.
I disagree with magicfingersny's recommendation of 2 condoms. As I recall from high school sex-ed, condoms aren't meant to be used in tandem and 2 actually lowers their effectiveness, as they can rub against each other. In any sexual activity, you should only use one, and since sex with a dildo is lower risk than sex with a person, there is no reason to get paranoid and ask for 2 condoms.