You can probably rent a studio at any of the DVC resorts for less than that during the first week of December. However, you may have trouble with availability because that is one of the most popular weeks for DVCers, so you'd better post on the rent/trade board ASAP if you are interested.
It would be anywhere from 80 -104 at points for 7 nights depending on where you wish to stay for a DVC studio room the first week in Dec. A 1 BR would be 160-200 points for the same time period. Points are renting from $10-$12 a point on the rent/trade board- sometimes less if there are time constraints on the points available. Only you can really decide if the cost you mentioned is reasonable for you. You could go to the Disney site and put in a request for a room only price for these resorts and see how they compare. As mentioned above you can probably do as well or better on the rent/trade board.
Old Key West would be the lowest price @ $137/nt. (or less depending on the price per point). That would be for a studio w/two queen beds. If there is no availability in December, the same rates would apply to the whole month of January. Also, keep in mind that DVC rentals do not have any room tax added to the bill (which in itself is quite a savings).