Note that for all the above you just need their open borders. If those civs are harmless (i.e. they aren't cultural or religious behemoths, they aren't ruthless expansionist trying to slip through your borders to settle on unclaimed lands on your side) then you can safely trade open borders and save money. Or actually get a few money if you are desperate for cash early on.
But if they aren't harmless, then just pay for their open borders and never give them yours. Even if they are your best friends, don't do that.