Hello, my cat is 2 years old and 11 pounds Male. He ingested a 500 MG tablet of amoxicillin he has vomited once and there have been no other symptoms in the hour since he has eaten it. I cannot afford the vet. Please tell me what I should do. Thank you.

Fortunately, even at that high a dose, digestive upset is still the most common concern we'll see. Considerably higher doses would still be needed for severe toxicity. It's been about two days and I would hope to hear that your kitty is doing okay. If the vomiting did not continue, we might still see diarrhea, though if that has not happened by this point, it is unlikely to.
While I understand your need to reach out, this blog should not be used for urgent or emergent matters, as it may take up to 2-3 days for a response. If conventional veterinary care is not something available to you, looking into a telehealth service like Dutch may be worthwhile, as you would at least be able to speak with someone who can triage your pet in a short timeframe.