Hi Fiona!
Thank you for bringing your question to the Disney Parks Moms Panel!
You are right on track with your research. You do not need a ticket to visit
Disney Springs, but admission is required for
DisneyQuest Indoor Active Theme Park. Current prices for admission are around $47 for adults and $39 for kids ages 3-9 (subject to change).
If your park tickets include the Water Parks Fun & More option, DisneyQuest is considered one of the "& more" choices so those type of tickets do not require you to pay separate admission.
Once inside, most of the games do not require any other payment. There are just a few attraction-type rides that have additional cost. With five floors of video games, we have never felt the need nor had the time to pay for those attractions. My boys (and husband) love spending an afternoon at DisneyQuest.
I hope this helps! Please let me know if you have any other questions.