I have purchased 3 military files from LAC at a cost including shipping within Canada of $66. (Canadian)
Most files will contain approximately 25 pages but some will have considerably more pages and there is no way to know.
The information in the files will contain the attestation papers, next of kin, pay documents and allocations of pay to next of kin, medical records, embarkation records to England and debarkation back to Canada, transfers within battalions and regiments including the dates, where the destination is on return to Canada and sometimes other inforamtion. Depending on what information you are looking for, these files can be very informative. If the soldier was injured, all details of his injury will be included in the medical records such as the date, the injuries, how long in field hospitals and which hospitals he recuperated in. The medical files are very complete with lots of detail. If you are trying to find which battles he was involved in the information on when, where and which regiments/battalions will make it easier to find the war diaries at LAC. The information in the files regarding transfers is also very detailed including almost to the hour when a soldier left one battalion and arrived at another.
I would suggest that you list the name, Regimental # and details that you are searching for and someone on rootschat may be able to find more information for you.
I have found the information to be very valuable and if you decide that you want the military file, I would suggest that you use the online secure site with a credit card and order the file. I don't think that you would find a researcher cheaper than ordering the file yourself.
Let us know if we can help with your search.