I'm leaning towards the Curve D3. Here is what I think I should order:

1. Dahon Curve D3 $360 shipped www.sunrisecyclery.com

2. Thudbuster LT 27.2mm XL $137 shipped. www.thudbuster.com

3. Dahon telescoping seat post (accepts 27.2mm) $30.50 shipped www.thorusa.com

It brings me a bit over budget, but the Thudbuster should be able to be used on other bikes in the future, as it is a standard size.