To learn to dive and get your C card figure about $600 to $900.00 soup to nuts. This is per person in a group lesson situation. Thats everything - books, pool work, classroom instruction, personal equipment (mask, snorkel, fins, booties), equipment rental, O/W dives, C card. If you do private lessons, it will be more.
Allow some time to get certified. Some Ads promis that you can learn in a weekend or learn to SCUBA over the internet, or learn to SCUBA for $99. Not a good idea. See whats offered for that price or that timeframe its not much. Its to get you in then youll be hit with the same expenses/prices as Ive listed above. It will take you at least 4 days to a week, with an Instructor. If you look at some of the old threads on this board, you will see this type of approach discarded. You need time in the pool working on your skills to feel confident. You need the interaction with your Instructor to gain his or her insights into diving more than you can get from just a book. After this, you will need two days of open water diving before a certification card is issued (min. of 4 or 5 O/Wdives).
With approx. $10K to spend you can buy lots of really nice stuff, get your certification, have a nice vacation and still have money left over. Your first step is think of how you and your family will want to dive.
I am a big proponent of learning to dive locally. Divers who do, tend to dive more often because the water is right there (so to speak) and they are comfortable in it. The problem is diving in the Northeast. will be in cold, dark water. You will need lots of thermal protection, hence, lots of lead weight. If you dive in the ocean then you will face currents and everything is brown. If you think you will be into wreck diving or looking for lobsters or spear fishing then definitely learn to dive locally. If you learn to dive in the North Atlantic, you will be able to dive anywhere. I loved it and dove it for 12 years and am proud to be considered a New Jersey wreck diver! But, this is not for all people and I understand.
If you think you and your family would only dive a few times a year at some sunny, warm resort with lots of pretty fish then find a nice Island (Grand Cayman is great! but, theres lots and lots of other great islands), or go to the Florida Keys, contact a few dive shops and ask about their course how much, how long, whats included, experience of their Instructors, how much pool time, etc. and pack the family and go. In a week youll be certified and have a few extra dives in as well, plus lots of on-land-time to do other things.
Or, you can do a combination of the two. Do the pool and classroom work in Mass. and get a referrel to some place warm. Not a bad option.
Now, for buying stuff outside of mask, snorkel, fins, booties, mesh bag to carry your new found treasures that should be it for awhile at least. See how you like your new found sport. See how much you are diving. You can rent a lot of stuff for many, many trips before it pays to buy. Now, when you rent you may not be getting the best stuff but it will be ok. Youll be exposed to other divers who have their own stuff and you might see something you like. Or keep researching. Look at some of the comments about equipment that are posted on this board from time to time. Just remember, we all have our brands that we love to love or hate.
Im sure youll get many more comments. I wish you well in your search and see you on the bottom sometime soon!