Bom dia,
I am not a Bergenser, but the ship I work on has Bergen as its base during the summer season so I have spent quite a few days there.
There is one major hobbyshop in Bergen which is part of the "Hobbyland chain" in Nygaten 3, a reasonable selection of kits, glue and other accessories.
Some of the department stores do also stock kits along with toys, one in "Bystasjonen" used to have a couple of unusual kits for sale.
You find a number of second-hand bookshops in Bergen, I have picked up some bargains there related to aviation and military history.
There used to be an IPMS branch meeting in Bergen Tekniske Museum (Science Museum at Møhlenpris close to the University),
but that area was closed due to water entering that part of the building last time I visited the museum - it is worth going there on a quiet Sunday if interested in old vehicles and the entrance fee is very reasonable.
If interested in aircraft should you try to find the way out to the Herdla Museum which covers the activites of Luftwaffes JG5 from the airfield.
Other museums I would recommend are the Maritime Museum (with bits of a Zero on show) and the new Fortress museum at Bergenhus.
Eders
Knut Erik