I have two experiences with that kind of deal.
The first one was full-sized three bedroom house with a pool and two car garage. There were only about 10 of us there but one woman was on the phone and I think it was to the person who used to live in the house.
I posted this story elsewhere, so when done here I'll come back later and post the link to that thread for more details.
Basically though I got it for $3K even. I thought I could double and I did. I took everything from inside the house (with no electricity on) and I took a week to do it as I was doing it myself with only a little help on bigger stuff.
There were two cars that were not included..one in garage, one is side yard. These people even left the dog....the neighbors rescued it after a few days.
I cleaned the place only to the point where everything was gone...even stuff in rafters of garage (except over the car left in there). Later the property manager said ... "You could have stood on the car !" JERK !
Here's the link:
http://storageauctionforums.com//index.php/topic,561.0.html*****
2ND place was basically empty and smelled of cat urine. Walk through the house took about 1 minute. Went to garage where the whole floor surface was covered two feet deep in trash. Old house had a "bend over" walk space underneath...a few things there.
There were only 5 of us there and the others were 2 couples. I took them up to $325. I would have been happy at $200 but I knew they wanted it and they got it. Heard from them later it was a break even. The fellow then went to work for one of the 4 major auctioneers in the area !
Here's the link on the 2nd one:
http://storageauctionforums.com/index.php/topic=1032.0Hope this helps...as far as the cleaning etc. Base your offer on what's in there but make it low. They've got a ready buyer who will basically clean it out!