Breakeven for each person is different. Here is my "back of the envelope" analysis for my situation.........your mileage may vary.
Usually go one holiday (week before T-day or week before Christmas), alternating each year to make max use of AP's. Take a couple of other weekend type trips (3-5 days) as getaways. Family of four. I have 350 points. On my holiday trip, 2 bedrooms are about $700 per night. Some locations are closer to $1,000 and there have not been too many discounts (there may be in the future however). I'll use an average of $5 per point for maintenance fees.
Cost of 7 nights at holiday (2 bdr)= 7 x $700 = $4900
Tax = 4900 x 12% = $588
Cost of non holiday nights (1bdr) = 5 x $400 =$2000
Tax = 2000 x 12% = $240
Maintenance fee cost on 350 points = $1,750
Less taxes saved = -$828
Less AP savings 4x $100 = $400 (I am aware this could go away and some won't use it in their analysis).
As you can see, tax and AP savings bring me within $520 of annual breakeven of ongoing expenses. Before becoming a
DVC member we would eat breakfast at various WDW restaurants. Average bill for four was about $30-40. $40 x 12 mornings = $480. We eat breakfast in the room (I know some won't want to do that) and the cost is under $100. Just eating at breakfast at the unit gets me close to breakeven.
Amortizing my purchase price is as follows. I bought AKV from Dis for about 94 per point and received 5 nights (developer points at SSR) 2bedr at XMas. Room cost for that ressie would have been $700 per night. I bought 200 points, so cost was about 19,000.
Bought 150 BWV resale for $80 per point and received 150 banked points, cost = 12,500 (clsoing costs included).
I have $31,000 into purchase cost (no small sum).
My developer points saved me $700 x 5 nights = $3,500 (yes I was going then anyway).
Banked points on BWV (if rented at $10) got me $1,500 (MF's were paid by seller). My cost to purchase is now $31-$5 = 26k. As stated above, taxes, AP savings and breakfast save me more the cost of my annual MF's, so now I need to amortize the purchase price. At $6,900 per year, my 26k get's eaten up pretty quickly.
The point I am making here is that DVC actually alters they way my family USES WDW. We eat dinner in probably half the time. Not because we have to, but because we want to. When we stayed in WDW hotel rooms, we never did that. The food cost savings are enormous when dinner is factored in. If you would never do this, then leave it out of your analysis, but for us, it probably saves another $700 per year .
I'm sure some will challenge the math and probably rightly so. But remember, if I did this for 5 years and sold, I will recoup some of my initial outlay. How much is open to argument, but even if I got 40% of purchase price, I would be way ahead. Also, I know that I could do it offsite cheaper, but for me that is not a comparison I am interested in. For the most part, I want to stay on onsite.