The application fee for a High Potential Individual visa is £715. You will also have to pay Ecctis to run a check to ensure your qualification is valid which is £210 if applying from outside the UK and £252 if applying from within the UK.
You must also pay the Immigration Health Surcharge which is £624 for each year you will be in the UK. This fee is paid up front.
You must also demonstrate that you have enough savings, namely £1,270, to support yourself whilst in the UK (the maintenance requirement). You will need to be able to show that you have held these funds in your bank account for at least 28 days in a row. Day 28 must be within 31 days of applying for the visa.
You will not need to show proof of funds if you have been in the UK for at least 12 months.