I already have a senior member account, but if the estimated price is really good, i might still consider buying an extra as an investment...
Well, this is not a Sr member account. This is a Potential Sr member account with ~80 activity. Thats why the price is lower.
nb: Potential btt account means, that activity is accumulated by posting at least once biweekly(more accurately each activity period). So just by posting you can increase your activity instantly.
I overlooked the pontential-part, but it still doesn't change my initial question: did you run in trough an account estimator, and if so, can we know the approximate price it was estimated for?