Best Alternatives to University Education

Best Alternatives to University Education

Sometimes it so happens that either because your interest is too
specialized or because you are in a small liberal arts college, your
college does not offer the courses you want to take but are usually
offered in some other colleges/universities.
Definitely, you do not want to change college because of 1 or 2 course,
and when you are nearing graduation (junior/senior).
What are best alternatives to such situations. Of course, I am looking for
alternatives that are well regarded Graduate Adcoms. (i.e. eliminating the
options such as self study, online video lectures etc.)
After I posted here, I thought, it might equally suit Academia.SE. There
reason why I posted here is to limit the scope to mathematics courses.