If not mistaken, diving and snorkeling in sipadan are almost the same price?
For other places, maybe quite big difference, but not for sipadan?

Scuba Junkie - same price
http://www.scuba-junkie.com/diving/

Hye Asern,

You may go for snorkeling to Sipadan island but not really enjoy unless u go as a diver . The current quite strong and you can only go near to the buoy as a few metre after is wall drop . Sipadan is a small island . I've been there with my family and my mother the only snorkeler and she the only one who snorkel at Sipadan at that point of time . For me if I go as a snorkeler not much enjoy but u may try

p/s : I will be going again this coming 25-29 Dec and stay @ Billabong Scuba 

agree with u nutella

First of all, are you a diver? (Do you have a diving license?)
3D2N including the arrival and departure day?
If so, you can only dive on the 2nd day.
Pricing around RM250-300/day for 3 dives in Mabul (Sipadan is more expensive of course).

If u dont have a diving license, i dont think there's any discovery dive for u to join in Sipadan, u can only snorkel there.
For easier and more relaxing dives, u should go Mabul, Sibuan, Mantabuan.

Discovery scuba dive is where the instructor will teach you the basic basics and then bring you to dive once. You won't go very deep, and the instructor will bring you around. It's a one-to-one thing, sometimes one-to-two if got many discovery scuba divers. Usually cost around RM180-200 per discovery dive and you won't get any license to dive or anything like that. Everything is included, all the gears and tanks.  You just have to go and enjoy, it is a one off thing which will take few hours of your time to introduce you to the underwater world.

Open water course is the PADI course for you to get your Open Water License. It consists of theory and practical lessons where you have to pass the exam to get the license. Usually cost around RM1200-1500 depends where you do it. This one, you'll have to sit thru videos, read the book and do theory questions. Also have to be tested pratically, like floating on water, swimming for certain distance, basic skills like clearing mask, bouyancy control, etc. The instructor will teach you all this and you are expected to learn and remember. It usually takes 4d3n if you do it all on the island.

Once you get your license, you can go for dives with a dive master. A dive master usually brings about 6-8 divers to dive, depends on how many customers they have also. They are like dive guides underwater. Per dive in Malaysia usually cost around RM100 or so. Might not include equipment rental. This one, no instructors will be watching you. The dive master have to jaga more than one so you have to look out for yourself as it is assumed that you have pass the test and know your basics already.

You can do Open Water courses here on the mainland which I would recommend, as you will have more time to complete and understand the theory part before doing the real thing. I personally did my course at Perhentian island and it was very stressful for me. There was no time to just sit and relax. Every free time that I had was to study and watch the video. I didn't learn much as well cause time was limited. However, I did my other courses on mainland first then go to island for pratical test. Those were very relax and I've learnt so much more compared to the first time I dive.
If you don't have a license, you can't take a diver package.
Diver packages are for divers with license. They won't give you discovery scuba every dive every day. They won't be so free to give you full attention and bring you down everytime. That's why discovery scuba is much more expensive than a normal dive for those with license. The whole point of discovery scuba is to introduce you to scuba diving.

I suggest you go take up your license first, then go dive.