I made a babywearing fleece jacket out of three matching $10 fleeces. You could do it with one fleece, three matching zippers, and an extra piece of fabric but at the time I was willing to pay $20 to not have to install 3 zippers. (It was going to be about that much anyhow, what with zippers often being $5-$7).
Anyhow, I used one fleece to make an insert - just cut the shape (Wider at top, narrower at the bottom) and added the zippers from that jacket to the insert. And the other fleece, I cut the zipper off and sewed it onto the center back of the third intact fleece. So I get front and back wearing for $30 and 30 minutes.
I only wish I hadn't made it in black - black is chic, until it gets covering in baby spit and cat hair. :( I'm lint-rolling that sucker like every day.