Spend the money on a digital monitor. We had one of the pucks sent by Health Canada, found out our basement had extreme levels (as high as 600-900 Bqm^3). The digital monitor shows the big trends. We had some equipment installed to remediate it, so it's better... But we'll be doing more work next year to try to reduce it even further.

The only thing worse than finding out how bad it was, was not knowing about it for 10+ years. This whole thing has likely reduced the life expectancy of my family.