I say this to be honest, and not to make you feel bad, but the fact is that you already missed out. Currently marketed resorts are selling at close to 50% more than what they first came out as, and are rising quickly. In my opinion the value has been completely priced out of DVC right now, and resale is the only way to go if you are looking for value. People talk about wanting to use their points for cruises, but oftentimes don't buy enough points to even have that as an option. Plus, you can take the money you save by buying resale and pay for one or two cruises in cash, and still have your points for that year. How many cruises do you really plan on taking?
Finally, I'm not sure if I'm misreading this, but it sounds like you and your brother's family are going in and buying DVC together, is that right? If so, I would strongly caution you against it. While it sounds like fun, you are essentially linking your finances to theirs. This is not good for so many different reasons.
Anyway, to answer your question...it's a sales tactic. Take your time and research DVC, you won't regret it.