Have you considered trying to make your own?
My first sewing project was my Karo Step down quilt I made earlier this month (posted up in the MYOG section last week) and it was surprisingly easy to do.
The total cost was around $135, 11.1oz of 850FP water resistant down. Total weight of 18.6oz.
I got my down from allied feather through Down Linens -16oz minimum order- ($103.5 for a pound I bought, so $71.8 for the amount I used in the quilt). 800 FP down is cheaper and I've posted a coupon code on gear deals the other week. Fabric, etc from DIY Gear Supply. I used 15D Impetus 1.0 which was $9.15 a yard, but you can get 15D Argon from Dutch Ware Gear for only $8 a yard, under an ounce per yard. He also sells precut widths of noseeum for baffles as well.
Making it yourself would probably be the most economical route and you can customize it to be perfect for you. It's a lot of work, but it's fun and you'll have a quilt that fits you perfectly.