The advertising budget primarily depends on your business goals:
Generally, $500 is enough for testing and finding profitable approaches.
The budget size also depends on GEO and vertical. The competition in the top-TIER countries is higher and accordingly requires a larger ad budget. Running offers with low payouts and simple flows (SOI) will require a smaller budget.
The minimum test budget for CPA campaigns is $50. But keep in mind that the wider the targeting – the higher the test campaign budget should be. Tier-1 and tier-2 GEOs are highly competitive, so we recommend setting more than $100 for the test.