Raffia Sources

True Raffia

• Wool and the Gang, Ra-Ra Raffia
• Fibra Natura, Raffia (photo, left)
• K + C, Raffia Yarn 
• Hamanaka, Eco Andaria 

Similar Vibes 

• Lion Brand, Rewind Yarn
• We are Knitters, The Tape
• Katia, Tahiti
• Plarn! Plastic yarn from grocery bags, DIY tutorial
• Cotton yarn in general (sometimes held double):
  Re-Line, Re-Up, 24/7

Note that not all raffia or raffia alternates share the same weight, so you'll want to make a gauge swatch. The good news though? You're probably making a bag (vs. a sweater) so final size is arbitrary anyway. I'd just go for it ;)