last two renos cost around 15K each (including demolishing walls, bulding walls, electrical fittings, floorboards and painting) - so far averaged 100K profit each on sale not CG.
I have never take out a 2 bed to become 1 as it makes no sense in terms of resale or revaluation.
Not sure about landed units.. mine are apartment and it is an absolute requirement to take out walls to build a room with a building permit. It' stated on the body corporate with MICM (a body corporate in melbourne)
Irrespective - why risk being questioned the room as a non 3 bedder by a potential buyer? or purchaser after signing the contract - and then they argue . for $660 is not that much to pay.
again - this is solely based on my experience dealing with council and body corp in melbourne. I can't comment about other cities or areas.