I would like to find out how to get my boyfriend and the father of my son a visa and how much it would cost and who to go to

There are a variety of visa options available. Are you looking to marry when he gets to the United States? If so, you will need to file a fiancé or K-1 visa petition. You will need to establish you are in a good faith relationship and intend to marry within 90 days of his entry. Once married, your husband would be able to apply for lawful permanent residence. Costs will vary depending the exact visa option you are considering. I encourage you to contact a few attorneys directly for fee quotes. You can read more about the fiancé visa at http://myattorneyusa.com/k-1-and-k-2-visas-for-fiancees-and-derivatives.