We (dad, mom, 17month old) just got back from Maui after a 13 night stay.
It was my wifes second visit and my first. We found a modest 2b2ba condo across from Kamaole beach park 3 for 170 CAD/night (
exchange rate).
It wasnt the newest condo but it met our requirements. I found it on airbnb so naming the building would be useless other than to say it has communal bbq which we used 6 or 7 times (steak I think is the only food other than bottled water that is cheaper in Maui than in Canada), and it also had a beach shower on its site of S Kihei Rd which was handy to do a final wash of some beach items.
If you are just going to the beach then you dont need a rental car but unlike Oahu I would rely on the Mauibus for anything. You will need a rental car.
Kihei worked for us for its price compared to say Wailea and Lahaina area.