Coinbase is very safe and cheapest. Another good exchamge is Binance p2p
You don't have to buy an entire Bitcoin at $45k. You can buy $10, $100, $500 worth etc. Each Bitcoin is broken down into 100 million parts called Satoshis. (Just like one dollar is broken down into 100 cents).
Why are you posting things that are so wrong? Coinbase is one of the most expensive.