There is no useful universal Google Ads budget
A sensible budget depends on search volume, click costs, conversion rate, customer value, margins and the number of services or locations being targeted.
Work backwards from the business outcome
Estimate what a qualified lead or sale can be worth, then define an acquisition cost the business can sustain. That gives campaign performance a commercial benchmark rather than judging success on traffic alone.
Budget must be large enough to learn
If a campaign can only afford a handful of relevant clicks each month, optimisation will be slow. In that situation it can be better to narrow the initial service or geographic scope than spread budget thinly across everything.
Separate media spend from management
Advertising spend goes to Google for clicks; management covers strategy, tracking, optimisation, testing and reporting. Treating the two separately makes it easier to understand the economics of the channel.