What features are using? Bing, Here and Mapbox all provide good products (as do a bunch of smaller map providers), but pricing varies a lot based on what you are trying to do.
We're just showing properties on a map. Nothing special.
I would start by checking what your traffic load would cost under Mapbox and Bing and if they're too expensive I'd start checking some of the smaller OSM based hosts mentioned in this thread.
If you need well-maintained mobile SDKs, Mapbox's pricing model is a lot more straightforward. If all you need is basic mapping on the web, OpenStreetMap is adequate.