Generally, an ad group costs 20 or 30 dollars a day. There is no fixed advertising budget, provided that your listing is optimized well enough.

If the profit of one of your products is 5 dollars

In the early stage, you can run an automatic ad to see the order situation and the words that generate orders. If you get 1 order with a 5 dollar advertising budget, you will not lose money. However, it is normal to lose money if you run ads in the early stage.