Not to add to your indecision, but something to consider- while you can always buy a unit on the resale market later on, this is a unique opportunity- since it will be passed down it will retain the right to exchange for Marriott Reward points and to enroll in the DC. A resale week bought on the open market, even for a great price, in the future will not have those options.
Those 3 weeks could be converted to 6550 DC points. You could use the points from the special season week and one of the sport weeks to book a high demand week in Aruba, for example, which you could rent and cover most of the annual MF's for all 3 units. While Orlando weeks don't rent too well, enrollment in the DC will allow you to book elsewhere and rent that booking and, if chosen wisely, you could cover your costs. Even renting just the points would basically be a wash, and you'd have use/ownership of the weeks when you can afford to use them.
There are many people buying points and spending lots of money to do so; the purchase price for that number of DC points is in the area of $65,000 today.
I know this probably falls into the area of rationalizing a purchase, but since you mentioned the cost savings of having a kitchen I have to say that when we purchased a few years ago my husband and I added up some of those silent vacation costs, and we came to the conclusion that for 5 people traveling eating in for breakfast, taking lunch stuff to the beach (we're not big lunch eaters but love to nosh), beverages (and we're not drinkers, so we were just considering the cost of soft drinks; if you add in beer, wine and other beverages the cost savings increases), and grilling for 2 nights (which we like to do just not to eat out every night), and subtracted the grocery store bill, we saved a good $800 or so, maybe more. Moreover, we eliminated the daily aggravation of where to go for breakfast- enjoying a leisurely breakfast on the balcony is a great way to start the day for us, and adds to the vacation experience. So the food savings alone for a family could easily offset the MF's just by eating in a couple more dinners, without detracting from the vacation.
While I am not a big fan of the DC program in general, the point conversion option may make this a very practical take-over for you, and I wouldn't be so quick to reject any of it.
I am guessing that, with MF's due next week, your Mom will have to pay the 2012 fees anyway; if that's the case, it would certainly give you more time to digest all of this and get more of an education as to what would be best for you. If the MF's is something you absolutely cannot afford then you should pass, but if it is something that would be difficult but doable it might be worth strongly considering, because with the DC point and reservation options open at other locations which command higher rentals, and/or renting the points outright, you would likely recoup most if not all of your costs. There are still some weeks that, even in this economy, consistently rent at high prices, even though the prices may be less than a couple of years back. On GregT's rental website you can see that points have been renting well too, which would be another way for you to simply recoup your costs for what you couldn't afford to use, while still retaining the ability to use them when you want to/can afford to.
Although my opinion seems to differ from a lot of the other posts here, I have to say I wouldn't walk away so fast. And, as much as it shocks me to say it (because I have found a lot of fault with the DC program how it was rolled out and points allocated), it is because these weeks should be eligible to join the DC that I would lean strongly towards taking them.
