Alright, I have a way for you to get the car for around 35 dollars a day out of LGA. Create an American Airlines account (no need for you to have miles in the account) and go to www.useaamiles.com Prior to making a search, click on AAdvantage member login and log into your account. Now, search for car rentals on the current page out of LGA; you should see economy cars available for 3000-4000 miles a day. If you click through to the confirmation page, it will allow you to supplement miles for cash at a 1.1 cent ratio. Using this method, you will be able to get a car from National on your dates for $35 a day. I just checked and they have many cars available for this price. Having done the same thing 2 days ago, I can confirm this method works.