What is a proper term to name amount of money and their currency? Like 100 USD, 50 EUR, 100 GBP - all are "amount", "value", "sum"?
"Amount" is the closest single word. "Amount in dollars" would be the easiest way to specify information you are requesting. "Amount and currency" if you ware in an area using multiple currencies. An accountant might be able to give you a more technical term, but it would be accountancy jargon. Amount due, credit amount, debit amount, amount deposited, amount credited, amount withdrawn, or amount included. If you're writing instructions and want to specify that the person following the instructions needs to indicate the currency, you'll probably have to simply state that requirement.
Based on US centric thinking, inside the US, money is dollars, dollars is money. For US citizens outside the country, we would always tack on the currency. 100 dollars, or 100 Euro. There is a segment of Americans who do not understand geography, and that other countries exist, and that they use different currencies, might not realize that other countries have currencies named dollars, and that USD means US Dollars. So for U.S. citizens, be specific and clear.
Bottom line, if this is written for US residents, and they need to specify the currency, you need to explicitly require them to "List the amount and currency."
The best I could come up with would be to simply ask for the amount of "notes" and "coins" you would like, and specify denominations thereof.
The different currency labels exist for the reason that not all of them are valued the same, so USD 100 is not the same as EUR 100. To generalize would mean some form of uniformity in the values, that just isn't there.
I would go for
cost if what you mean is "how many units of some currency can I exchange for a good or service". In scientific terms, that would be a function of currency, as long you don't care which currency your sum is in. That is, any amount of some currency has a perfectly same value as a certain amount of any other currency and vice versa. For instance, an item priced at 100USD would be priced 86EUR or 74GBP or 11182JPY in some hypothetical world where taxes, exchange interests, inflation and that sort of things don't exist.