"Executor" has a specific meaning. It's a legal term referring to the person who manages a deceased person's estate in accordance with that person's will. It's pronounced differently too, the emphasis is on the second syllable. Here is a definition with pronunciation.
"Executer" is pronounced with the emphasis on the first syllable. It means the one who executes. That may mean (arguably incorrectly) to execute a will as in the above. Among other meanings it may also mean the one who carries out the execution of a person, as in hangman. Many dictionaries don't even list it as a word (executioner is much preferred in the hang-man context), but here is one that pronounces it.
"Executor" is absolutely the preferred way to spell the legal term. Some (myself included) would say that the "er" would be incorrect in that context. If I were using it to mean hangman, I would use the "er" and pronounce it that way. But even in that context, some would argue that it's a made-up word.
For your purpose, I would endeavor to avoid it entirely by coming up with a different word.
The short answer: when used as a noun, the "price" is the amount charged for something, and the "cost" is the amount paid for something.
When a person is discussing buying something at retail, the most common noun used for the amount charged by the seller is "price."
I wanted to buy a white cotton jumpsuit, but the price was too high, so I didn't.
When used as a noun, "cost" refers specifically to the amount paid by someone for something. It is most often used in an accounting or business context.
Our cost per item is three dollars and our gross revenue per item is sixty dollars. That's a fifty-seven dollar profit on each jumpsuit sold!
It is not exactly wrong to use "cost" as a noun in the same way you would "price":
I wanted to buy a white cotton jumpsuit, but the cost was too high.
However, this is not as idiomatic, at least in American English; it sounds a bit melodramatic. You would be more likely to use "cost" as a noun where it is understood that you are discussing the impact on your finances, rather than the amount the store asked for the item:
Sure, it was expensive, but the cost isn't what's important: it's how the jumpsuit makes you feel.
Confusingly, you can use "cost" as a verb to describe the amount charged for an item:
That's a lovely jumpsuit; how much does it cost?
"Price" as a verb is used only for the act of setting a price:
Why would you price these jumpsuits so high? We poor students need jumpsuits, too!
Best Answer
"Revocate" means to call back, recall. For example, to send a message to troops to retreat. I have an excellent vocabulary, but was previously unaware this word existed, so I think it's reasonable to assume its use will usually raise eyebrows among even very fluent, well-educated speakers — most of whom will assume you misspelled "revoke". Some dictionaries mark it as obsolete, and I'm not surprised.
"Revoke", on the other hand, is a fairly common word, meaning to undo a previously-valid decision or law. For example, to cancel a previously-granted permission to do something.
If you want to use revocate, you should seriously consider simply saying "call back" or something similar instead. Even in formal uses, this will likely be the best choice; borrowing from the previous example, a military text that mentioned a general "recalling" his troops would be perfectly natural, while one that mentioned that general "revocating" his troops would be hard to understand.
"Revocation", itself, has nothing to do with "revocate", other than by etymology. It's the noun form of "revoke". So one might refer to "the revocation of an order", meaning its cancellation.