I would use those translucent plastic/cellophane bags you can buy at any craft store. I just bought clear bags with red polka dots at Michaels - I can't remember the price but they were cheap and came with twist ties. There are great Valentine's Day stickers and tags on etsy that you can have personalized (some are even sold as PDFs).
I might steal your idea! Any tips? Did you microwave the crayons to melt them? Did you melt them individually to keep the colors separate or swirled?
JMS
Mommy to DD "HH" 2004
and DS1 "MH" 2005
& DS2 "JJH" - My very Irish baby!