[Ch3m]

Does anyone know what are the most common carbonates (out of the alkali or alkali earth metals, except those with Rb, Cs, Fr, and Ra) and the cheapest in order?

Where can I look up the prices and rarity of each carbonate? Thanks.

[Arkcon]

Conventionally, the cheapest reagent of any type you can buy is the sodium salt, what with the planet we're sitting on having ocean's of the stuff.  Potassium comes next, it being really important to plant nutrition, so large amounts are mined/used.  The real cost of a reagent has more to do with the purity you want, and the costs of producing it, shipping it, etc.  and will depend on the vendor.