No, you always pay the same price wherever you buy your ticket.
At the end of 2009 the Swedish Work Environment Authority decided to eliminate the use of cash on buses as a result of theft and threats to drivers in recent years. This also means that coupons cannot be used for payment on board.
If you have already bought a ticket and then decide to continue your journey into another zone, you can buy a bridging ticket from the driver. But you have to do this within the change time for your original ticket. Then you will not need to pay twice for the zone you are changing in, but will still have to buy two separate tickets for your trip. The change time is calculated from the time you buy the last ticket.
If you travel between two stops in the same or different zones but via a stop in another zone, your ticket or card must be valid for travel between all the zones involved. Even those you are just passing through. If, for example, you travel from Korsvägen to Frölunda Torg via Mölndals centrum, the trip will cost the same as a trip between Gothenburg and Mölndal, even though the final destination of your trip is in Gothenburg. If you are unsure, you can always check what applies to your journey in Travel planner.