Yes you are right. Our smart contract is already available on our website's main navigation. Just click Github on navigation page.
You are right. They must be audited. Problem here is, for example we are a little startup company and it is impossible to afford an audition by a third party. They are too expensive. What we could do is that we open sourced our smart contract which can be viewed by anyone and anyone can check. Of course some level of knowledge about the code is needed. But someone from the forum that has this ability can do it.
Also we would love to get audited if someone can make it free of charge

. We wish, it was cheaper to request audit.
Well, if it's open source then you can just share here if you have a GitHub or just make the smart contract available to the public. The thing with third party audit is expensive and I don't think there will be a free of charge even in this forum. It takes time to audit and it is even done by a team and not just by a single individual.
I think making your code available to the public was the best course of strategy for people to view it. It would reciprocate later on if there's no malicious stuff on your smart contract, people would really want to try that lottery.