i want bustabit.com clone
i am ready to pay 20 to 30$
...
20$ to 30$ won't cover the price for an hour of work for a good programmer. Your best bet is to buy the licence from Ryan, because if someone agrees to do this for you for the price that you are offering (or for free you may say) it may plant a backdoor in the code.
Anyway, even if you get the code, you need to hire someone with programming skils to maintain the website, so maybe it's not such a good ideea to start a business that you don't have the knowledge to maintain.