Ok...
I did some research. For your dates, adding in the EA membership, the rate dropped to $141.34 after all taxes.
According to the Disney Club website you can get a free Emerald Club Memebership:
How to Redeem:
Call 1-877-603-0486 for your fee-waived membership application.
I'm not sure if you can do it over the phone/over the web, but you can try! I know when I signed up with BizTravel (which is no longer offereing it free), I did it over the web and got the number immediately.
If you have to mail in for it, you could get lucky and it be processed quickly--before your trip. Either way, you can get the memebership rolling so that you'll have it for next time.
Best of Luck!!!