A few suggestions:
Using Penn subscribed databases sends you through the Libraries "proxy." The proxy is the key that unlocks the subscription paywalls. You should never have to pay for a journal article. Talk to your librarian if you run into trouble connecting to an article. 99% of the time they can help you get the article quickly.
If we don't have direct access to an article or book chapter, you can "Email me a chapter or section" (the Libraries will make a copy from the collection or request from another library--turn around time can be quick!) or request books from "Pick up at Van Pelt" which, if we don't have available at Penn, will trigger a request to request from one of our partner libraries. Log into the Libraries' collections catalog to see all of your options.