Marriott generally has a "soft landIng", bringing elites down only one level if they don't meet the number of nights per year. They also have allowed buyback. Last year I believe Gold to Plat was 50000 points (and you can buy up to 50000 pts at $12.50 per 1000 points).
This year they apparently have a lower point threshhold during a special offer during March, but indicate that it will be higher levels after March 31, 2009:
https://www.marriott.com/marriott.mi...elitereinstate
*** My email request was personally responded to in less than 40 minutes, with status reinstated (and points deducted), even though the phone line is "closed" over the weekend. ***

Buy Back Your Marriott Rewards Elite Status for 2009

As one of our valued Elite members, we understand that your travel needs vary from year to year and that occasionally you might not have the required number of stays to maintain your Elite status. But we know how important Marriott Rewards benefits are to you - so we are offering you a limited-time opportunity to buy back your status for 2009 using points that you may already have.

Here's all it takes to reinstate your level:

Points required to buy back Platinum status - 40,000 (a savings of 20,000 points)
Points required to buy back Gold status - 25,000 (a savings of 15,000 points)
Points required to buy back Silver status - 7,500 (a savings of 12,500 points)

Remember, if you don't have enough points in your account, you can always buy up to 50,000 points every year. (Note: Full purchase would be $12.50/1000 x 40 = $500; x 25 = $312.50; x7.5 = $93.75. That still beats the cost of 75 nights, 50 nights and 10 nights in a hotel MANY times over!)

This offer is valid through March 31, 2009 and allows only one level of buyback, which must match the Elite level you enjoyed in 2008.

Once your status has been reinstated, Marriott Rewards will send you a new valid membership card for your restored Elite level.

How to Do It: Two Ways to Buy Back Your Elite Status

1) Simply call Guest Services at 1-800-321-7396 (toll-free in the U.S. and Canada), or

2) Email us at Marriott Rewards ([email protected]) with your information. If emailing us, include your name and Rewards number, then copy (or cut-and-paste) one of the three options below:

Switch my Elite status from Gold to Platinum status for 40,000 points (or)
Switch my Elite status from Silver to Gold status for 25,000 points (or)
Switch my Elite status from Basic to Silver status for 7,500 points
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Example of What to Include in Your Email:
Name: B.A. Marriottguest
Marriott Rewards Number: 123498765
Switch my Elite status from Basic to Silver status for 7,500 points