You can spend however much you want on Google Ads on a monthly basis, you set your own budget. What you’re doing is paying for clicks. If you are a jewelry shop in Wichita, Kansas and you want to get found for jewelry shop keywords then you’re probably paying about $1.20 per click. If 20 clicks cost you about $24 and you end up getting one sale or at least one person in the door, and they end up buying a ring or some small piece of jewelry which overall cost you $20, then it was worth it. 

If you start out with $400 in one month and you end up getting eight customers out of it with each customer spending about $600 at your shop or your store or location, then that was $400 well spent. Google will show you how much more you could’ve advertised in order to gain even more leads by spending more money. So if you spent $400 but your ads only showed 15% of the time then you know you can increase your budget by 85%.