Your logic kind of escapes me. If going direct costs $30, why would using a middle man i.e. the LDS be cheaper? Is the LDS going to eat the extra $10 that it costs? If anything, I would think that going through your LDS might cost more money since they are using their time and resources to get something for you that you can very easily get for yourself. Not only that, but it seems like you would have to make at least 1 trip, if not 2 to the LDS to pick up your card, unless you expect them to eat the cost of mailing it to you. And you just can't walk into your LDS and not buy something!! That's against the law. So now, a $30 card probably winds up costing you a couple of hundred.
BTW, when I got my CPR card, it only cost $5. Now I think that is a true "cost" price. And that included mailing. And when my son got his Basic EMT card, complete with a photo ID, that cost nothing. Now if he loses it, I have no idea how much it would cost to replace.