There should be some Black Friday/Cyber Monday sales going on now. But rather than just concentrating on price, best to stick with one of the major name brands (Samsung, Sandisk etc) and only buy from one of the major chains preferably in person at the store. Buying these online from Ebay and even Amazon can result in getting a fake.
For a phone you don't need the absolute fastest card available, the phone won't be able to take advantage of the full capability and it will operate at a lower read/write speed anyway. Any Class 10 SDXC card should be fine for this application.
