Tackle the high cost of almost everything in New Zealand

I am very concerned (embarrassed even) about the ludicrously high cost of almost everything in New Zealand, especially in light of our relatively low wages. This is severely limiting people's quality of life, and leaves virtually no discretionary spending ability for many. The perpetrators of this seem to consistently blame "distance & isolation" and "the small size of New Zealand's market", but to me this is codswallop. I believe it's because we are too small for an effective competitive market to operate and so we end up with a couple of dominant players who effectively control each sector. There are numerous sectors that need to be looked at, but groceries and building products would be good places to start as these have the most impact on peoples everyday budgets. I would really like to see some proper and gutsy investigation done so we can get some transparency across these sectors. Once we have this transparency we can decide as a country what we may be able to do about out it.