This is a really old thread, but I just got back from Playa del Carmen and wanted to share the results of my quest to find the best dive shop in Playa.
I contacted 19 dive shops in Playa and Tulum and asked them all the same questions. 17 dive shops responded. Scubamoble came out on top. They were the most flexible (e.g. accepted cash, cards, Paypal and did not REQUIRE a deposit), the most accommodating (e.g. arranged for a night reef dive when most wouldn’t), and were the least expensive (both in terms of fully inclusive prices and they don’t charge unreasonable currency exchange rates)! While many responses from shops were canned responses that didn’t directly answer our questions, Scubamobile provided detailed information about all aspects of their services. When we showed up for our dive, all of our rental gear was set up and waiting for us. The equipment was very well maintained and quite new. The shop is clean, well laid out, and even has a small shower. Our dive guides were all top notch - both in terms of experience and personality. On our third day, we realized that we had to check-in for our flight at the time we would be underwater. Scubamobile overheard and offered to check-in for us! Prices will change, but at this time quotes from the various stores for a 2-tank cenote dive (inc. gear, computer and cenote fees) were as high as $180 USD. 1-tank night dives were as high as $110. Scubamoble was a *whole* lot less.
Here is my admittedly somewhat subjective overall ranking of the dive shops based on price, flexibility, and attitude.
1 - Scubamobile (excellent responses)
2 - Playa Scuba (not as good of a shop, but was our fall back plan)
3 - Infinity2Diving (top shop in Tulum)
4 - Tank-Ha (discount for 3 days of diving)
5 - Reef quest (quite a negative response, but otherwise looked ok)
6 - Scuba10 (mid-priced and provides lunch at cenote restaurant)
7 - Scuba Revolution (pretty expensive, but looked like a good option)
8 - Scuba Playa (discount for 3 days of diving)
9 - Mexico Blue Dream
10 - Dive Shop Mexico (2nd most expensive shop)
These shops either were too expensive, too much of a machine, didn't offer the services we needed (e.g. night dives) or didn't respond to additional questions:
Blue Life (most expensive shop)
Scuba Libre
Dive Tulum
Dressel (machine, required reef dive before cenote dive)
Dos Ojos Scuba (cash only and no ocean dives)
Beyond Diving (no dive computers)
In summary, if you want personalized, friendly, professional service at a great price, we found that Scubamobile is the best dive shop in Playa del Carmen.