Concatenating sublists with ":"

I'm trying to build a string using ":" and then write that string to a file. Function gets two lists that include strings, which are amounts of money

[["$123,123,123", "$68,656", "$993,993,993,993", "$123,141,142,142"],
 ["$60", "$800,600", "$700,600,500", "$20,200,200,201"]]

It should be written as

"$123,123,123":"$68,656":"$993,993,993,993":"$123,141,142,142"
"$60":"$800,600":"$700,600,500":"$20,200,200,201"

Currently I have something like this:

def save_amount (amount, moneys):
    with open (moneys, "w") as file:
        for i in amount:
            moneys_s = str(i)

How to proceed?