When I check availability there, it shows as sold out, so you have the added hurdle of simply getting into a sold out location. Given the pricing you have, I assume this is one of their take the 90 minute sales tour deals. I recently received a similar offer for their Flordia locations. The small print makes it clear that it is an advance purchase deal, and once you book it you will be charged, and must give 7 days notice to change or reservation or face a $99 fee. So how do they explain charging you, but saying you don't have confirmed dates?! I would start making noises about complaining to the Arubian time share sales regulators about their deceptive sales practices - I would think that is the last thing they want. And when they tell you that their location is sold out, you can offer to let them put you up in the (nicer) Hyatt down the beach. Here's the small print on the Beach Place Towers (Ft. Lauderdale) offer I got - which I assume is fairly consistent with the Aruba offer:

Offer sponsored by Marriott Vacation Club International as an advertising plan for its Vacation Ownership program. This program is designed for individuals or couples with a combined annual income of $60,000 or more and ownership of primary residence is required. Attendance at a 90-minute sales presentation is required for this Preview offer package, which includes 4 days/3 nights accommodations. Failure to attend the sales presentation may result in the charge of the standard retail value of the Preview offer package. If married, it is required that both husband and wife attend the sales presentation together. The retail value of this package is up to $745. Preview package price is based on accommodations at a per room charge, not per person. No adjustment will be made in package price when purchased for travel by fewer than two adults. Additional surcharges will apply to holiday periods. The retail value of the Water Taxi cruise is up to $20. One offer per family, no groups. Offer is valid for up to two (2) adults. Standard retail value of accommodations is an average seasonal rate of up to $225 per night. Standard retail value of $50 Marriott Merchant Dollars is up to $50. Retail value of the Water Taxi Passes is up to $20. Certificates are not redeemable for cash. No cash back in whole or in part, if total purchase is less than certificate amount. Certificate will be issued upon completion of the sales presentation. Accommodations will be provided by Marriott’s BeachPlace Towers in a single guest room (hotel style room). Alternate accommodations of equal value will be used, if necessary. Upgrades are available for an additional charge due to the need for larger accommodations. This offer expires 12/15/2000. All travel must be completed by 03/31/2001. This is an advanced purchase package. Transportation, additional expenses and applicable taxes, if any, are the sole responsibility of the recipients. A credit card is also required at check-in. Additional nights may be purchased at the seasonal rate. This offer is made on a space available basis, is non-transferable and non-refundable. Any changes to your reservation require 7 days advance notice to avoid an additional charge of $99. You must have a written reservation for this offer.

Employees of Marriott International, Inc., Host Marriott Corporation, its affiliated companies, and their immediate families, previous participants and current owners of Marriott Vacation Club International properties are ineligible for this offer. Offer is subject to change without notice. Offer void where prohibited by law. This offer not valid in conjunction with any other offer. Marriott Ownership Resorts, Inc., 6649 Westwood Boulevard, Suite 500, Orlando, FL, 32821, is the developer, an equal opportunity credit lender and a subsidiary of Marriott International, Inc. Any acquired names and addresses may be used for soliciting sales of time-share periods. This offer is made in compliance with the law of the jurisdiction in which the project is located. N.J. Reg. No. 97/4-834. As of June 2000, the current price of deeded weeks for Marriott’s BeachPlace Towers range from $8,800 to $20,400. Prices subject to change.