If you can believe this (they are still in business and doing this type of work as well as being a reverse distributor), I used this company in the 1970's to do the pharmacy inventories of around 7 hospitals with printouts of all items so you could check their work, which was usually accurate:
We found that most inventory services you would contact provide totals, with no way to check their work for accuracy. This company provided detailed printouts so you could discover any major errors if there were any. Since they have done Johns Hopkins Medical Center and Stanford University Hospital, they do travel to all parts of the country.
We use Capital Inventory out of Woodastock, Ga. I have used them for the last 8 years. I have always been pleased with their service. Our accounting department comes over after they are finished and does a mini audit while they are still there to make sure the numbers are correct. They do travel all over the United States. If you would like more info just let me know!