<human>: Not sure if this has been posted about before, but I couldn't find anything when searching for it. 

Anyways, I recently booked a rental car for my trip to San Francisco. I originally started looking at Budget, and for just one night my rental would have costed over $110 for an economy car since I'm 21. 

I did some research, and I found out that if you have a USAA membership the underage surcharge is waived, and you can save up to 25%. So, I went back and signed up for USAA, and then went to Budget's site again and it went down to only $65. Woohoo! 

To make things even better, there was a coupon for USAA members that got you one weekend day free.. Seeing as I would be there for more than one night, I tried seeing the price from Thursday-Sunday using that deal.. The price ended up being only $6 more for 2 more days.. 

So, moral of the story, keep shopping when it comes to rentals, and **sign up for USAA**. It's a financial service for veterans and people in the US Military, but *anyone* can sign up and take advantage of their travel deals.

Could you distill the essence of the text into 1-3 sentences?
<bot>: sign up for USAA for free if you are an underage driver, the underage surcharge will be waived and you can find HUGE savings.