1 Box 192PCS 4x13MM Natural Tube Stone Beads Strands with Hole Synthetic Turquoise Column Cylinder Gemstone Loose Spacer Bead Bulk for Jewellery Making Bracelets Necklace DIY Crafts Supply

These aren't the most expensive, but they also aren't the most uniform and are from Amazon, plus they are 13x4 Lima Beads has a lot of 9x5 and 14x7 at varying prices and materials, and is a great bead supply, but they also aren't quite the same size... FMG has a few square tubes (here are a couple options of those) They had one tube bead that was round and roughly this size that I found If you are open to working other sizes of tube beads then there are a lot more options on sites like Kraftika, but I understand it would mean making adjustments to your pattern.