Los Cabos is not an area known for its shore diving. If you are concerned about costs, shop the ops for a discounts on a multi-day dive package & bargain hard. The Baja California is still Mexico.
As for thermal protection, it's somewhat idiosyncratic.
To put it in perspective, below is a piece, in part, from my June '00 "Ask RSD" column in "Rodale's Scuba Diving":
"Have you ever been out on the street in the spring or fall and noticed people wearing everything from shorts & T-shirts to full coats with hats & scarves, all apparently in comfort? Well, things are no different underwater. This comfort is highly variable among individuals depending on such factors as percentage of body fat, age & tolerance to thermal discomfort. Other determinants, like how many dives a day over how many days you are planning, are also important. When you ask "What wetsuit should I wear?, you'll get answers ranging all the way from "just a bathing suit" through "5 mm full."
The question is better asked: "What water temps can I anticipate at my destination?" You'll receive a pretty accurate answer to this, and then can decide what's best for you based on your personal thermal comfort needs.
It's always a good idea to come thermally prepared, just in case."
That having been said, multiple sources have been reporting Los Cabos water temps of 72 degrees plus/minus a degree. Personally, if was doing multiple dives over multiple days at that temp, I'd take a 5mm full & beanie.
You're going to have such a good time.
DocVikingo
