Used vs. new

My humble advise to you is to buy good, used equipment with a proved reference or near reference status for no more than the current used market value or less. Ask yourself the question - how many of the new/current hifi equipment would stand the time and eventually become timeless and desirable in a long run? Not many. Learn from the best and proven equipment without loosing a lot of money and don’t gamble on new equipment with no proven track record. This advise is not only about saving money, but the right and only way to learn.  Learn from the best, proven equipment, and not from the new with no track record. Just because the company has long record, it doesn't mean that the new equipment they introduce on the market will be up to par. 

Newer speakers from the same manufacturer are not always better sounding and can just be different. I would look to buy a good used pair and use any left over funds to upgrade somewhere else

@OP. If your choice is between a D4 or D2/3 802, get a used one - they are more natural sounding than the D4 (within the overall context of those speakers generally having a distinctive house sound). Make sure an second hand pair is fully tested though as spares - tweeters in particular - can be difficult to get.

B&W : you may get better speakers for less.

B&W`s are known to be bright. You may need to spend more on your electronics to tame that bright sound, and have some amp power to drive them.

I own the 804N. Great bass. It puzzles me that others have claimed lack of bass in their B&W`s. 

I don't have experience with the B&W models mentioned here but owned 2 pairs of old B&W models for more than a decade, and I agree with few comments here that new is not always better. In my case, New and more expensive sound worse than old and cheaper. I owned the B&W CDM 1 SE close to 15 years. Midway through the ownership, I tried the more expensive model, N805. To my ears, the cheaper CDM 1SE sounds better than the N805. A matter of preference. I sold the N805 after about 3 months.