We rented for a week from Vacation in Paris and the company was lovely to work with (one reason we chose them is that we were able to get the key mailed to us in the States ahead of time) I have no idea if, given new Paris rules about short term rentals, they still have good/affordable options - our experience is a few years out of date.
Paris France Vacation Apartment Rentals, Paris Holiday Rentals | Vacation in Paris