Are there cheaper alternatives to ACM and to IEEE Xplore digital libraries? The faculty in which I am currently working is planning to subscribe to the ACM Digital Library and to the IEEE Xplore Digital Library. I am not pretty sure how much are the real costs of the subscription because for example in:

http://librarians.acm.org/sites/default/files/ACM_DL_PricingGuides2014_NoTabs_V19_Academic.pdf

it appears something about tiers; I suppose that for a small access to this material oriented only to students that are doing their bachelor's final year projects, we will be in tier 1. About IEEE I still do not have information about it.

In any case, I would like if there are another alternatives to those two digital libraries, excluding Arxiv because a lot of their articles have not been peer reviewed.

Any suggestion?

PD. Update information:
We would like to access to articles about all the fields of Computer Science, the access would be for around 20 students maximum each month (that is the number of students enrolled in their last bachelor project). We need only the articles to be reviewed for their research as supporting literature.
If you are needing frequent access to particular articles published by ACM and IEEE, then ACM DL and IEEE Xplore are really the only ways to go.

However, if you are needing to be able to find and reference general background information across a broad range of computer science subjects, then there are informal access methods which also work quite well.

First, Google Scholar is very good at finding non-paywalled copies of PDFs.  This is especially the case for computer science, where many conferences have very liberal policies about self-archiving and where many people strongly believe that material should be made accessible online.  Some organizations, such as AAAI and AAMAS just always put everything online for free as a matter of policy. Even IEEE and ACM are fairly liberal about this and rarely interfere with authors who do not follow the letter of their law.

Second, the ResearchGate site has an option for privately requesting copies of publications from authors, and most computer science authors are quite willing to share (again, there is a strong "information wants to be free" culture in much of the community).

The efficacy of these approaches varies from subcommunity to subcommunity, but it sounds like the type of general access you're looking for may well be sufficiently served by them.