Train Stockholm to Lofoten?

You've obviously missed it. There is an overnight train from Stockholm to Narvik.

SJ states that I can book tickets through June 2 on their website. However, the website only sells ticket to Narvik through the end of March. RAILNINJA is the only agent I can find that will sell tickets for August. RAILNINJA states Rail carrier opens ticket sales for this train on or around May 27, 2024, but you can make an advance reservation for your tickets right now.

I don't know if RAILNINJA charges a large profit or whether they are paid a commission. How quickly do these tickets sell out? Can I wait unit May and buy it myself? Any advice is appreciated.

Kelly

Take a deep breath and relax, there is no need to stress out over these tickets. The tickets are not for sale yet so noone can sell you tickets for this train in August yet. Although Railninja tries to trick you into paying them to buy you a ticket when they go on sale. Note the fine print you qouted, they will not sell you a ticket for August! Railninja should be avoided at all costs, they are known to be expensive. I've seen people comparing Railninja's prices with the actual ticket costs and have seen examples of Railninja charging €60-70 for a ticket that would cost less than €20 if bought direct from the company that actually runs the train.

Come back in May or June and buy the tickets yourself. Trains are not Taylor Swift concerts, they don't sell out in minutes after the tickets are released. It can happen that they sell out quickly, but that usually only happens to popular departures around major holidays or events. For a train to Narvik in late August I really can't see any reason to worry about it selling out.