I always gave small gifts and told him after dinner he will get one if we go on the potty all day long. Let me tell you he ate dinner well those nights.
Perhaps you can give him something small but at the end of potty training he can get the guitar.
I found that I had to not mention the reward as that is all he focused on so I would only mention it once in the morning. I did not give him anything else. I also gave him all the power - tell mommy when you have to go potty. If he started to go we ran to the potty. If I ever asked him if he had to go - he always said no. He now does not like when his pants are wet and runs into the bathroom.
I just started this a few weeks ago. We still have accidents. I only gave prizes on the first 5 days - little match box cars.
I am not sure if this helps or not. Good Luck