on an average whole sale deal , what should I aim for my profit to be ?

whatever you want it to be but I would shoot for about 4,000 or more

That is purely up to you and your negotiation skills. I know some wholesalers who are happy making 2-3k on a deal. If you're working nicer areas you should be able to do better. When I was focused solely on wholesaling I've made as much as 20k on a deal and as little as 3.5k. My average was over 8k. If you are working with 100k+ homes this is doable. If you are working with 35k homes in C class areas it is not. 

Really I just try to leave meat on the bones for the next guy. If you give someone a respectable return they will come back to you. Too many people get greedy and burn their ability to build long term partnerships. Which should be your goal... Here's why... 

I got a call from a seller asking if we would give him 45k for a home. I made one phone call (to someone who had bought several properties from me) and we had it sold (assigned) for a profit of 10k. Had I screwed them over on the first few deals that wouldn't have happened. Be conservative in your ARV estimates. Be a little liberal in your repair cost estimates. Everyone is sick of wholesalers over promising and under delivering.