Sodium Bi-Carb Sub - Baking Soda?

This has been widely tested and for most it results in significant GI distress that far outweighs any benefit.

The biCarb product from Maurten is formulated/encapsulated to slow digestion and minimize the GI distress.

As far as making it cheaper - you can buy it in various "potencies" which actually just provide more of the product (not actually more potent). David Roache taked about how he buys the higheset potency and then just splits it up into multiple doses, which reduces the cost. The problem is that the system only comes with one dose of the hydrogel, but it sounds like he just mixes it with regular gels to a similar result. Its still expensive, but if you split every serving in two, that makes it half priced. I haven't tried this, so YMMV.