It depends most on how your network is configured, or if the target employs geoblocking or not.
If your firewall allows the sending of arbitrary packets, even malformed ones, and the target does not care if you are in Ireland or Argentina, a cloud-based scanner works the same as using your own IP.
On the other hand, if your firewall "sanitizes" packets, discarding malformed ones, or your target drops packets depending on your location, it can be worth pay for a cloud scanner. How a target handles malformed packets are a good indicator of OS used, application running and so on. If your firewall "fixes" the packets, that can mask your results.
Another consideration is technical support. Commercial cloud scanners will usually offer help if you run into problems, and help interpret results. If you are skilled enough to do a scan without assistance, that may be unnecessary.