Cassava roots are cheaper at Food Town, and cheaper still at various Asian markets around town such as Viet Hoa, Hong Kong (on Bellaire), etc. Expect to pay around $.89 to $1.50 per pound.
----- Hong Kong Cafe 9108 Bellaire Blvd Ste A, Houston, TX 77036
Certainly all HEB carry it fresh, and probably most other big stores. You can also get it frozen from Goya. Just boil 30 minutes and remove center string, then further prepare as you like. One of my favorite foods. Kroger and HEB carry the frozen Goya cassava.