Free: Contests & Raffles.
I don't agree that down is something to stay away from. Knowing the conditions you might encounter really dictate whether or not down is a suitable choice more than anything.
I went camping with some buddies this weekend, and he hung up his bivy style Hammock tent. Not sure the brand, but I think it is one of these.http://hennessyhammock.com/catalogue.html
...The down side to floorless tents are mice can get in...and the girlfriend thinks the spiders have free range (she's correct).
No condensation problems with the bivy?