I just sleep on a yoga mat. I got it for $20 at Target. Then again, I live in Miami so the temperature of the floor is never an issue (in summer I sleep directly on the floor to take advantage of the cooler temp).

I slept on the floor for a good three years during university (both hardwood and concrete). I originally did it cause I was too cheap to buy a mattress, but once I got used to it, it was pretty nice. I used a couple different layers of wool blankets (real old ones, pure wool; make a nice thin, warm cushion - warmth can be important if you're sleeping on a floor... especially in Canada), as well as a camping foam mat (about .25" thick).

If you're just planning on trying out the floor without buying a Shiki (they're usually made of cotton, btw), go down to a camping store and look at the cheaper mattress alternatives they have. You live in Vancouver? Go to the MEC (Mountain Equipment Co-op). Never been to the one in Vancouver, but I've been to others across the country and you can never go wrong there.

Then just play with various blankets you've got around to find a good material/texture/added thickness.

The cheaper futon mattresses at IKEA are fairly thin. You might try that. When my husband and I first got married we got probably the cheapest wood frame and futon mattress available at IKEA (read: bottom of the line anywhere, probably), and it held us over for a good year until we could afford a "real" bed. I still kind of miss that futon.

Futon mattresses are generally made of a thick cotton. Very little loft or movement. Generally, the cheaper the better as the more expensvie ones actually have some springs or foam in them for cushioning. I slept on one for several years in my 20s and never had back pain. You might find that getting a bottom of the line futon mattress from a Target or similar is just as cheap as one of your alternatives.

If you have a blanket for your bed you can probably just fold it into three and use that. I usually sleep on a carpeted floor but I used a blanket to sleep on concrete for about a month and it wasn't too much different.

Definitely don't get an air mattress; those things are awful.

Why don't you buy a memory foam mattress topper (1"-2" thick) and put that directly on the floor? That should work well for cushioning your hip & shoulders, as well as providing a wee bit of support for your back, neck and legs. Are you planning on going pillow-less as well?

you mean on air bed maybe?

I slept on a Japanese futon mattress for a year while living in Japan. They are just like a western futon mattress, but much thinner.

Right now I am sleeping on an old Therm-a-rest and a yoga mat. Together they are probably still a little bit more firm than a Japanese futon (and look much less sophisticated...)

I have a king size mattress and was also looking for a futon. Eventually I had an epiphany, "What about shipping pallets?" Low and behold, I did a googling of "pallet bed frame" and found this blog - http://remodelthishouse.blogspot.com/2011/07/diy-pallet-bed-frame.html

So now I'm e-mailing all my friends that work in shipping/receiving to see if they have any 42"x42" pallets we can have to test this out. We are moving soon and my current platform bed is very, very heavy, very 80's in style (black laquer with gold trim - UGLY), has no under-storage capabilities, and it SUCKS, which is why I'd rather dismantle it and give it to goodwill instead of taking it to the new place.

P.S. if you are anywhere near a ULINE shipping company shop, they sell new pallets for like $8-$10 each. That means for a king sized bed frame, you would be out $40 plus any coupling and wood screws to keep the base together.

How about a camp mattress. Its a thinnish piece of foam found in most camping stores. It is often laid on the ground under a sleeping bag for a bit more comfort. It could be useful for camping out after you get a futon living in a beautiful place like B.C.

I've been sleeping on a high density 3" memory foam mattress topper on the floor for 3 years, and just love it. Considering getting a platform and trying it on that, as I don't love getting up from off the floor at 3:00 am when I'm half asleep but have to pee. I sleep much better, and it alleviated significant back pain from sleeping on a typical mattress with another person and the "rolling in" and uneveness of it.

I sleep on a Japanese mattress-- it's just a few inches thick, stuffed w a straw-like material, and smells sweetly of outdoors. Unlike cotton, there isn't a flattening to the floor below, no 'sinking in'-- it is quite solid. I'd say try to find a firm cheap futon mattress to test.