Have rented a convertible for many trips to Hawaii. Rentals were usually Hertz with a AAA discount, or more recently Alamo with Costco discounts/coupons (exception of used an independent once on MKK since they had the island's only convertibles). Got a very inexpensive multi-week convertible rental from Alamo once when I booked it far in advance, but I modified the booking when they had a last minute specials email.

General observation that I'm seeing higher prices for Hawaii convertible rentals through direct book channels now during peak periods in 2011. Trying to book Thanksgiving week for $350 or less with everything added in, but I'm coming up with quotes of $100-$200 higher.

While I would far prefer to have more transparency and flexibility by booking through traditional means, I might try the Priceline route this time...or just settle for a hardtop if they won't accept a reasonable offer.

Also, are there other bidding sites other than Priceline that offer car rentals that anybody is aware of? I've used other auction websites for lodgings but don't recall seeing others that offer rental cars (other than a white label fixed rental price on some websites).