What tools/platforms for QA testing of mobile applications should be used?

Question

Software testing

We develop several products for various customers. We have recently introduced regular manual QA testing into the development cycle, which has given excellent results. However, there was a problem: the tester did not have enough devices. All iPhones are needed, and all popular Android devices, as well as web development, various combinations of up-to-date browsers and OS are needed.
Actually, I wondered which platform to use. The prices there are very different: from $19 to $200+ per month. Any advice?
In addition to QA tests, we only have unit tests and database load testing. We chose manual QA testing of client applications because we believe that this will minimize the number of bugs that get to production, and also a good tester will always notice inconvenient UX moments that designers and developers missed. Plus, it's relatively cheap. However, I'm not entirely sure if this approach is correct.