I use a simple method for my internal users:
1.) Service costs.
2.) Consumables.
3.) My salary.
4.) 20% for the unknown.
         Add the costs then divide by 500. A 50 week year/ 5 days per 
week/mornings and afternoon. Evenings and weekends don't come into my 
reckoning but have the same charges. The instrument is booked solid weeks 
in advance so the charges must be quite fair. Although you always get some 
users who complain, 'I've no grant money left.' No money no time or use now 
pay later.
         External users, that's something else, the price really goes up. 
The microscope has to be replaced and they are buying expertise so the 
costs must reflect this.
Ian.

>Date: Wed, 05 Apr 2000 13:03:38 -0230
>From: "J. Foote" <jfoote@morgan.ucs.mun.ca>
>Subject: Confocal microscopy
>To: "histonet@pathology.swmed.edu" <histonet@pathology.swmed.edu>
>
>Hi,
>Can someone recommend a source or method, that might be used to track the
>workload of a confocal microscopy unit.  We are in the process of obtaining
>such a unit and will be required to bill all users, both internal and
>external, of the facility.  You can write me directly at
>jfoote@morgan.ucs.mun.ca.
>
>Thanks
>
>J. Foote
>Histology Unit, Medical School Laboratories
>Faculty of Medicine
>Memorial University of Newfoundland
>St. John's, Newfoundland, Canada