There are no set fund amounts. The person coming needs to show their own funds in a bank account that will fund a 3 month visit, airfare, insurance etc. Estimate $2k per month and add airfare/insurance. Show as much as possible. Funds are just one part of visa approvals. Travel history, times to home country etc. are just as important. A 3 month visit is a long time so ties to home country will be more difficult.How much do we need to show as finance let say for 3 months?