I believe he's trying to gauge the rate of "inflation" of the membership price to see if $5500 is worth the cost in the long run.

Just looking at the annual membership now ($300 annually), that's over 18 years before you'd start to see an ROI.

However, the OP is taking into account how rates increase by looking at trends -- using 2005 rates alone is not the best bet.

I'm curious to know annual rates from the past.

If it was $350 for a lifetime in 1980, annual fee would have been something like $20(!?!?!) if comparing 2005 Annual vs. Lifetime costs.