You can get an air pump with tubing and air stone even cheaper than below. Keep in mind, a lot of people are doing this with no air pump at all (Kratky method).

Here's one that's 40 GPH for $8.99- https://www.amazon.com/Pawfly-MA-60-Aquarium-Gallon-Accessories/dp/B073DWVX5P/ref=sr_1_3_sspa?crid=HF2HVFOQD2OY&keywords=cheap+air+pump+with+stone&qid=1672663217&sprefix=cheap+air+pump+with+stone%2Caps%2C128&sr=8-3-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyMTBEVkpONE1QNUhOJmVuY3J5cHRlZElkPUEwMTUyNzQyUElWMDZQWlRLTjZWJmVuY3J5cHRlZEFkSWQ9QTA4OTc5NzIxODJZRDVMMlIzU1FPJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

That's big enough for a small container. Here's another though that's 100 GPH for only $12.99- https://www.amazon.com/AQUANEAT-Aquarium-Adjustable-Outlets-Hydroponics/dp/B0899NTXBF/ref=sr_1_7?crid=HF2HVFOQD2OY&keywords=cheap+air+pump+with+stone&qid=1672663217&sprefix=cheap+air+pump+with+stone%2Caps%2C128&sr=8-7

HTH. It's all pretty simple and straightforward.

I bought this; plus some black tubing: https://www.amazon.com/gp/aw/d/B0899NTXBF?psc=1&ref=ppx_pop_mob_b_asin_title I went with the dual output pump because I have 2 aero gardens at the moment. I can't give a longevity review, but it works well enough so far! Sounds like a fish tank, but my gardens are in the basement so the sound doesn't bother me.