None...
Because it's not one of the vaccine's box listed side effects so on the 1 in 25,000 chance it happens you can sue for medical costs...
That's not gonna help you if you can't afford, or perceive you can't afford, the ER visit to begin and you die in your home. It also won't help you because the federal government decided that covid vaccine manufacturers aren't liable for side effects. I don't disagree with you on principle and I think I understand what it is you're trying to say. That said, answering what the cost of treatment is with well you can sue for medical costs is ridiculous. Also, Myocarditis has no singular treatment. You can treat the symptoms and hope it goes away, or go in for a valve replacement.
To answer your question Scotty, the cost of treating myocarditis varies on a lot of factors, and it varies wildly from hospital to hospital; at least here in the USA. Keep in mind that some hospitals have cost sharing plans or coinsurance plans, and depending on the treatment, scans and tests, cardiac specialist costs, and length of stay the price-tag can swing by a huge margin. With a quick google search I found a projection report from the early 2000's that says the average cost of treating a heart attack was around $21,000.00. Surely the cost has gone up in the 20-odd years since then; and especially with the price gouging thanks to socialized medicine initiatives.
Now for my opinion. Take it or leave it.
As with all illnesses there are risks with and without treatment. Risks that need to be taken seriously. Risks not just to your physical health, but also your mental health. I find that for me, the best thing to do is as much research as I can and make an educated decision. I do not trust the media, our government, the CDC or the WHO to tell me what is and isn't good for me and my family. I trust hard facts, not political spin. For covid the risk/reward is simple to me. Do my personal health issues, age and living conditions warrant getting the vaccines to avoid complications from getting the full blown sickness?