One way fare on either the Market-Frankford Line or any bus is $2.50 cash. You must have exact change if paying the cashier or operator. Neither can make change. Quick Trips are available for the Market-Frankford Line from the Fare Kiosks located in the stations. The kiosks accept credit/debit cards and cash [no exact change needed!]. Note, a Quick Trip is a one-way ticket, good for 24 hours. It can only be used at the station from which it is purchased.
Your best bet, is a SEPTA Key Card. Like a Quick Trip, it is also available from the Fare Kiosks but unlike a Quick Trip, it is reloadable and reusable and it works on buses. The SEPTA Key Travel Wallet allows you to pay as you go and you'll receive a discount for each ride ($2.00 versus the $2.50 cash fare). You must load a minimum of $10 [which will get you 5 rides]. Funds in your Travel Wallet can only be used to pay for one (1) person. It cannot be tapped multiple times to pay for anyone traveling with you.
Best part – your SEPTA Key gets you more than just a ride. Flash it for discounts on food, drink, museums, sports, shops and more. Click here for a full list of Partners.