adriciu,
Check out Judi of Croix. I think they have a website. Their phone number is 340.773-2123. There is no "Judi" anymore, but the current owners are very nice people. They have helped me out a couple of times when my car had to go to the hospital. Their prices are as reasonable as anyone on the island.

Ric

Another good local choice is Centerline Car Rentals

centerlinecarrentals.com

Depending on where you are staying, you may not want a car for the entire time. I've often advised people to take a safari tour with Sweeney http://www.gotostcroix.com/safaritours/ on their first full day to get the "lay of the land" and then rent a car to go to places they want.

I've rented from Gold Mine ($99 for 3 days in low season, somewhat higher in high season) at 340-773-0299 and been very happy. I've also used Olympic (888-878-4227) because they have a 10% discount coupon in the publication "St. Croix This Week" - it's pink and available for free everywhere. It's also available on-line at http://www.print2webcorp.com/news/virginislands-sc/splash.asp so that you can use it to check things out.

Ditto on Judi of St. Croix. We used them and she offered to leave a car for us at the airport or bring the car to the hotel. We actually took a taxi to the hotel so we wouldn't get confused trying to drive to the hotel and then just left it at the airport when we left that day to go home and I guess they came and picked it up later. I checked around and their prices were very good and she was very helpful when she brought the car to us. Gave us a map and offered suggestions on where to go.
I would definitely rent a car for most of the time you are there as there are so many things on the island you need to see.

YL