Hey mama! I think best bet mo talaga ay Carousell or Facebook Marketplace, madaming moms doon nag-post ng preloved plain white baby dresses, super affordable din usually! One of my mum friends swears by those groups kasi hassle-free lang, pwede mo makita agad ang condition ng damit, at pwede ka pa mag-negotiate pa ng presyo. Try posting din sa local mommy FB groups in your area, madami doon ready mag-share ng gently used stuff nila. Good luck sa paghahanap!