Who pays for the primaries?

[jimrtex]

When states run primary elections are they paid 100% by the tax payer? Meaning voting booths, etc? And if so, why? Primaries aren't even required by the law or the Constitution, shouldn't the parties pay for a portion of the costs?

If states require parties to nominate by primary, they have to pay for them.

It doesn't really matter whether the states or the parties actually conduct the primaries.