It's difficult to set a specific number as a recommended budget. It depends on the targeting you choose and the purpose of your campaign.

If you're targeting a narrow or niche audience, it can make sense to start small — say €1,000 or similar.

If you want to reach a wider audience, you might want to increase your budget to at least €2,500 in order to see a significant impact.

Keep in mind, you can start small and ramp up. There are no hidden fees or start-up costs. Adding several smaller campaigns won't cost you more than one bigger one.

Self serve has a minimum budget threshold:
€250 / $250 / £250

Other currencies have the equivalent value of the amounts above.