I will checkout the thrift shops for used dressers; I figure the drawer sides and backs are around 1/2" and some older pieces are made of poplar and the like.
I looked at Home Depot by me for poplar thin boards and a short boards, less than 3 feet long, 1/4" thick and around 5" wide was $9 in change! I can buy a whole dresser for $20 and scavenge the drawer sides and get a dozen boards... I get it's a "Learning Curve"