Hi, to make website like binance, programmers must start from scratch because it is not secure to use scripts created by other programmers. when you want crypto exchange site, security is the most important thing, all hackers will try to hack your website and steal the money/coins. beside it, you will need one server for website, one for authentication system, and one server for each coin, if your website has 10 coins, you will need 10 servers for 10 coins. of course, only bitcoins and ethereum demand bigger servers, the rest of coins are small. so, all in all, you need server configuration, you will need several servers administration, not only making website. now you understand more.
all in all, 100 days for programmers to make website and deploy servers and to test all of it for security. so, you would have to pay in milestones/steps, because it would be risky and expensive for me to pay everything in advance: 3 server (for website, for bitcoin and for authentication), for the beginning, later we can add more coins, when we finish implementation of one coin into website. so, we would need 3 servers for 100 days until we finish all of it. BTC server should be 2GB RAM and 500 GB HDD.