I don't think you will be happy with the outcome if you are limited by only using material that Spotlight sells. For absorbancy you need bamboo (or hemp) and to stop leaks you need PUL or something similar- unless you are going to buy covers.

If you want to try MCNs, you are probably better buying a few on sale or second hand and trying them rather than home made ones first off. Else you may just get frustrated and give the idea away before you see if cloth is right for you.