For the purposes of this resource we have focused only on the cost of implementing identifiers, not on the substantial resource and effort required to make collections items available online, such as building a web presence for the collection, digitising it, or having it catalogued to a sufficient level where information about the catalogue can be put online.

To add persistent identifiers for metadata into collection items, while there generally is not a cost to embedding identifiers within metadata, there will be a cost associated with the staff time of identifying, inputting and validating the identifiers. The schema of collection management systems may need to be updated as well as the fields and display of those identifiers on any website. This may require development time from an internal staff member or a supplier.

Locally managed URIs such as CETAF Stable identifiers only require a dedicated data domain as best practice, which can be set up by a developer in a short amount of time. A machine readable version requires slightly more time, but it can be measured in days rather than weeks. Maintaining persistent identifiers has a cost, but only in so far as web pages need to be maintained. ARKs are also free to use.

Utilising third party PID services can have a cost such as a subscription or membership cost to the provider that may or may not need to be supplemented with a cost per identifier created. This depends heavily on the cost of the service and service provider you decide to use. For example both Crossref and DataCite provide DOI services to organisations but operate on different costs bases. For example, in the UK, you can join the DataCite consortium administered by the British Library at a cost of approximately £1,100 per year with a fee of €0.80 per DOI up to 1,999 DOIs and there is banded pricing for larger numbers of DOIs. Crossref have a tiered membership model based on annual revenue (e.g. $275 for revenue <$1 million) with an additional charge per DOI. Those services have different metadata requirements which will need to be considered but come with support such as monitoring for broken links and usage data.

The Dutch Digital Heritage Network (DDHN) in the Netherlands ran a project from 2015 to develop persistent identifiers in heritage organisations. As a result of this project, 35 organisations implemented Handles within their collection management systems. They found that it was possible to implement PIDs via third party providers such as Handles via SURFSara with an ongoing cost of approximately €1,500 per institution per year. The first year included additional set up costs including set up of workflows and data preparation of an average €15,000, which were covered by the DDHN project.

Adding PIDs to metadata

If you need to create identifiers for metadata elements, e.g creators or collectors, this can be done using free or paid for services. The British Library's ISNI Quality team operate a paid model where you can request an ID to be created for £5 via their portal. Wikidata items can be created for individuals for free. These are subject to community curation and validation so may be deleted if they do not meet the criteria for notability.