There's an eBay seller called Franks11 where you can buy a variety of 1930's prints in various size cuts for a decent price.
http://www.ebay.com/sch/Sewing-Fabri...30%27s&_sop=15
I haven't bought the 1930's there, but that is my go to place for muslin. They have great customer service and quick delivery. The only downfall is that they do not take PayPal. I call them and give them my card #.