Hi Andrew.

Here are 5 Powerful Alternatives to Google Maps API and they are cost-effective:

1. OpenLayers

2. TomTom

3. Mapbox (Facebook and Snapchat's choice for mapping needs)

4. HERE

5. Mapfit

Please have a look to this very informative article: 

nordicapis[dot]com/5-powerful-alternatives-to-google-maps-api/

Maybe you should consider integrating one or more of them with UNA.

I would rather pay a reasonable fee to run an affordable map service with UNA than rely on Free map providers. Most of them are just jokes!