Flash: Buying the Creative Suite (CS for shorthand) is a very good deal so long as you'll use the programs. All but the cheapest CS package includes Flash (and the Patriot Computer Store has prices lower than the Adobe site).
An alternative is to buy the $29 month-to-month Creative Cloud. If you need it for this semester but are unsure of how much longer, this could be a great way to go.
With either approach, do take advantage of the free 30-day trial at the start!