I made a haramaki--japanese belly wrap--yesterday that I'm loving as a warmth measure, and that commentators are saying are functionally identical to maternity bands. It's an extremely low-cost way to experiment with a belly band--and you can easily play with the amount of support you want.
I cut off the arms of a thick t-shirt, cut open a sideseam, and then re-stitched the sidesteam, on a slant, to make a tight tube that covers my upper hips to the top of my kidneys. It took me 5 minutes, and I can't sew. If you can sew, you could put two t-shirts together to make a thicker band, or put a second seam on your tube to tighten the waist, or fold the cloth in half to provide more support. Or figure out how to make the haramaki from an old, shrunken angora sweater and then tell me how. (sweater is sitting next to computer.)
Fancy tutorial here:
How to make a Haramaki
and the immediate gratification, 5 minute commitment, approach here: