I hear Utila off the coast of Mexico has the cheapest diving in all of south/central america. I am supposed to be meeting up with a buddy of mine in August/Sept-ish. We are both from Vancouver and really looking forward to some tropical diving. It'll be a first for both of us.
From what he tells me, Utila is supposed to have dirt cheap rentals, and boat chaters along with really kick ass dive sites. Talk is cheap, proof is in the pudding. You can bet for sure I will be posting a few threads about it after I return.
In support of what Kayla said earlier. My dive club is still raving about the wonderful Keystone Park site just inside the Washington state border. Shallow dive(less than 60 ft) but just teaming with life. Our instructor saw 5 ocotopus among tons of other neat little critters. There are even photogs that travel up from LA, San Diego area due to the amazing life at Keystone. I think that says a lot in itself.
Now, ifn' yer willing to go a little further north to BC, Canada, you are in the realm of some of the best cold water diving in the world. LOTS of wrecks to dive, no penetration necessary to appreciate them. Amazing current dives can be found all over Vancouver Island and lots of smaller islands, Port Hardy, etc. Great charters up here to.
All the best,