Assuming you’re in the US, you can charge whatever, with a few limitations

-You cannot jack up prices on essentials during a state of emergency (no doubling the price of food as people are stocking up for a big hurricane, for example)

-If you have a contract to provide a good/service at a predetermined price, you cannot increase the price for whoever you contracted with while the contract is in effect

-certain goods/services like some utilities and some types of insurance may have a cap on the percentage of profit the company can take or a minimum on the percentage of the cost that goes towards the actual service (under the ACA, 80% of medical insurance premiums must go to paying for medical treatment; electric companies can only take a certain percentage of profit off of infrastructure investments and must otherwise provide electricity at cost).

-Most monopolies are illegal (so you cannot buy all the toothpaste companies and then charge $50 for a tube of toothpaste once your competition is gone)

I think that’s pretty much it. Anything else? Go nuts.