I was adopted when I was a new born the parents that adopted me wanted me to know who my biological family was I had contact with my real mother but never really knew who the real father was. I was given a name and I have meet him maybe twice when I ask him if he really was my real dad he said he would never admit it until I paid to get a dna done unfortunately I never knew how to go about this so I just dropped it and forgot about it. Than about a week ago someone my aunt works with asked about me and told my aunt that she was my sister so once again I would like to get ahold of this guy and try and find out if he is are not. Not only that I would also like to know for medical reasons I have kids of my own and what if something was to happen to one of them and we needed a medical history
Your help on how to go about doing this and how I could get one that didn't cost me a lot of money cause I don't have much to work with.

You could ask him to take a test... but as an adult... you can't make him if he doesn't want to. You will however have to pay for them yourself if he agrees. Prices might vary depending on where you live... so you would have to ask around.

Do a search on DNA testing labs. Find one that can test you both. Know that this will not be usable in a court of law.