Business purchase/value advice???

I have an opportunity to take over a local and established business. I'm looking for advice for what this is really worth.  Here are the nuts and bolts;
Total equipment/vehicle value est. $50,000
Business established 12 years locally.
-Business name and phone numbers
-List of 200+ customers, addresses, prices, all customer histories
-Existing rental agency arrangements representing 100's more properties annually
-He also does window cleaning for the same properties which I'm not opposed to taking on as well.  All window related equipment included as well. 

He is asking $185,000 which seems a bit steep to me.  Although I have not seen profit/loss reports and will hopefully see these soon.  I welcome any and all advice.  Thanks for the time and hope to hear some good advice soon.

annual sales?  you have a right to examine his books.
might be best to develop your own clients as most of his will go elsewhere when he goes.
But, it is your money.  Spend it however you want and then you can only have yourself to blame if the mine runs dry.