I've seen some "non-Medic Alert" associated bracelets at jewelry stores in the past.
Medic Alert is a paid service and not just the bracelet (or whatever piece of jewelry you pick out) that you wear. The ID is usually engraved with a general "warning" like, "ALLERGIC TO PENICILLIN" or "TAKING ANTICOAGULANTS" along with a 1-800 and an identification number that any medical care providers (cops, EMT's, nurses, doctors, etc.) can use to get more detailed information about the individual's health status.
As I understand it, you get to decide what's shared and what's not. If you have HIV/AIDS and you don't want that information to be listed as part of your MedicAlert bracelet, you can do that. They'll only list what you tell them to list.
Usually it's sent as a fax to the doctors office, hospital, or emergency room where you're being cared for. They may also have an Internet system for exchanging information as well, I don't know.
I've been mulling over the MedicAlert thing for quite a while, just haven't gotten around to deciding if paying an annual fee (I think it might actually be charged monthly, but I'm not sure) is worth the kind of "protection" it is designed to provide.
Besides, I'm not keen on bracelets, anklets, or necklaces really and most medical care folks won't check wallets unless it's the only way to find identification and usually it's actually a police officer who does it, the assumption being they would be more accountable and won't steal from you.