The seemingly on again / off again deal is back on again at Amazon. Through June 27, spend $150 or more on Britax at Amazon and get $50 off your order at checkout. Make sure you go for the free Super Saver shipping. More details at the site.
The less you spend, the greater discount you'll be receiving, percentage wise. You'll be saving about 18% on Marathon, 20% on Decathlon and Diplomat, and 15% on Boulevard.