Buying a Bar (well at least the building)

[Gil Lieblich]

I am what i would consider to to the investment world of real estate. I own a few small properties (condos) that I rent. Now I have been in talks with a good friend of mine who is attempting to buy a bar in a college town. He used to manage the bar and knows the business after being involved for 15 years.
SO the bar is unique and potentially a great business opportunity. he is in the process of raising capital to buy the operation and has asked me if i wanted to buy the building. The building is quite expensive at around 800,000 and basically would take all of my capital to purchase. I know as a general rule its not good to do business with a friend but it is a great opportunity. I am having two issues...
What is an appropriate return that i should be asking for as with my residential property i have always tried to find approx. 6-8%.
My other issue is his long term goal is to purchase the property from me as he would need it to be attached to the business which i understand and agree with but I have always been a long term investor with thoughts that i buy to hold for my retirement in thirty years... So how do i price a buyout in lets say ten years? As this ties up my capital is this a smart move to get involved.
Again this some what new to me so i apologize if i seem ignorant or have not given proper detail...any thoughts advice or criticism will gladly be accepted.

[Bill Gulley]

Takes all of your capital, like putting all your eggs in one basket? Bad idea, imo. Who brought you this "deal" someone who want to run it? Hmmmm

If you aren't familiar with the bar business how do you know it's a good deal?