The question whether to purchase digitising equipment and hire digitising personnel or simply to out source digitisation, is an issue for each institution to determine.
However, please keep in mind the fact that digitising equipment is very expensive and represents a huge fixed asset cost as well as the fact that once an equipment purchase has been made, in all likely hood better equipment will be released in the following years and you will be left with poor performing equipment in the interim.
It may be better to always out source digitisation and let the service provider bear the fixed asset equipment costs and deal with the associated technological obsolescence of the equipment.
However, one must keep in mind the logistics of the management of the print material submitted for digitisation.
You do not want to lose valuable print material in transit to the service provider and back!