There are a few members on here that make and sell beds that you just add your own pillow. I bought mine from Traci, aka Harley ridin Chopper. Her beds are called Snuggle Sleepers. I can find you the link if your interested. Extremely well made. It has a back like a pillow sham, and you just insert a standard pillow. Just let her know what colors or pattern you want, and she will try to find it. Her beds are $50 shipping included.
DazyMae and pookeypeds also sell similar beds that you just add a pillow. Their beds are super cute!
Or you can get a Tiger Dreamz trundle bed. Heather aka cprcheetah can get you a good deal on a sack type bed. They are gorgeous! You don't use a pillow. They are a "sack" or "bag" but you can roll them down and create a bed our lay it completely flat to create a blanket/mat. It's a 3 in 1 bed.
Just google words like
What your looking for should pop up.
They sell them on Etsy.com too. I just bought a cute cupcake bed. They are called Bratz Sax. I can't think of the sellers store name at the moment, but her name is Holly. Her stuff is gorgeous!