The Ticketmania.com page has posted a special announcement today; it says that all tickets they sell which are ordered through Monday will pay the old prices, but that all orders placed from Tuesday on will be charged the new rates.
I've had nothing but good experiences ordering through Ticketmania in the past, and the free shipping is also a bonus. My confirmation email from them today mentioned that due to so many people getting in under the price increase deadline, tickets will not be mailed until 4/6.
Hope this helps.