GP100 Trigger replacement

[Dave44]

I have recently obtained a ruger gp100 I think its an old mounty gun from Gander Mountain. The problem I would like to rectify is that it has double action only. can't I change the hammer to a type that I can use my thumb and thus make it single action?
1-any guess on $$ ?
2-do-it yourself?--i'm fairly handy
3-$$ to have a gunsmith do it?
Thanks in advance--great place you have here THANK YOU--Dave

 

[Old Fuff]

The problem is getting a hammer. I don't believe they will sell them outright, but they might put a new one in your revolver. Check with Ruger's customer service department at: www.ruger.com