The answer depends on your own country's economic circumstances, but here in Australia the "cost of living" has increased by about 520% between 1974 (when the TV series began) and 2006. This is based on change in the Consumer Price Index, released by the Australian Bureau of Statistics.
So $AUD6m in 1974 would have the same purchasing power as $AUD37.2m in 2006.
I guess you could say Steve Austin would be The Forty Million Dollar Man in today's economy.