Revenues and costs
In Table 4.1 we summarize PEAK revenues. The actual total was over $580,000 (the sum of total revenue in the first two rows).  The first and third rows report annual revenues, with 1999 adjusted to reflect an estimate of what revenues would have been if the service were to run for the full year (it ended in August 1999, but only six months of content were included, and prices were adjusted accordingly). On an annualized basis, two-year revenues were about $712,000.
Between the first and second year of the service, the number of traditional subscriptions substantially decreased: this occurred because two schools cancelled all of their (electronic) subscriptions. By reducing the number of journal titles under traditional subscription, the users of these libraries needed to rely more heavily on the availability of unused generalized subscription tokens, or they had to pay the per-article fee. We see from the table that the annualized revenues for per-article purchasing are seventeen times higher in 1999 than in 1998, and that the 1999 generalized subscription revenues (annualized) are 8% lower than in 1997-1998.
A full calculation of the costs of supporting the PEAK service is difficult, given the mix and dynamic nature of costs (e.g., hardware). We estimate that total expenditures by the University of Michigan were nearly $400,000 during the 18 month life of the project. Of this cost, roughly 35% was expended on technical infrastructure and 55% on staff support (i.e., system development and maintenance, data loading, user support, authentication/authorization/security, project management). Participant institution (IPL) fees covered approximately 45% of the project costs, with vendor and campus in-kind contributions covering another 20-25%.  The UM Digital Library Production Service contributed resources to this effort, reflecting the University of Michigan's desire to provide this service to its community, and also its support for the research.