Avis Car Rental Pricing -- WHAT?

So I went comparison shopping for a rental car. I want to rent in Madison, WI (MSN) and return to Milwaukee, WI (MKE) - Budget - $258 for SUV - Hertz - ~$500 for a mid-size - Avis - either $273 or $1455 depending if I pay now or when I pick it up. The 'Pay Now' option help seems to indicate that there are discounts applied. Image above is from when I used IE on a windows box after the WebChat help agent said it was a browser issue. ( all three browsers Chrome, FF, and IE show same results )

Chat started at 12:41 20 Jun 2012 
Jeff : Just looking at prices... why is the 'Pay Now' option ($1455.00 ) so much more than the Pay later option ( $273 ) ?? is that right --?
[You are now chatting with Mary.]
Mary : Hello Jeff, thank you for visiting Avis chat service. My name is Mary.
Jeff : hi.
Mary : What browser are you using?
Jeff : Chrome
Mary : I would recommend you to use Internet Explorer.
Jeff : I am on linux -- that is not an option
Jeff : I tried firefox --- it is presenting the same data
Mary :  This would be an error with the browser, I would suggest to clear the cookies cache and history. Close all the windows and try it again.
Jeff : Is the $273  a per day cost and the 1455 a full cost?
Jeff : This is the first time i've used the avis website - there would not have been any cookies or cache .   ( I am a Web Developer )
Mary : Jeff it is a browser issue.
Jeff : Could you just tell me how much it would cost for the lowest class car to rent at  Airport code -MSN  and  return to Airport code MKE  from  6/27 to 6/29?
Mary : Keep in mind all drivers must be at least 25 years of age with a valid drivers license and a major credit card with the same name. Your rental may be subject to a drivers license check at the counter. The estimated total including taxes, fees and unlimited mileage would be 341.55 USD.
Jeff : thank you --  if i decide to go with avis -- I will call in a reservation 

My Coworker Naz reminded me to use "shibboleet" next time.