solution to indoor humidity problems

—Edited—

My current apartment has bad insulation and
I'm considering getting a dehumidifier and also planning to move next year. My budget is a bit tight and I want to avoid moving twice if possible.

People who have cleared the humidity problem in older and not very well insulated buildings, is a dehumidifier enough to tackle it?

People who live in well insulated RC buildings with ventilation system, how much does the build quality help with humidity and your indoor air quality in general? And what’s the reasonable price to pay for it within Tokyo?

Thanks a lot!

by uynah