If you want to charge a friend "fair price", there are probably many ways to look at it. Personally, I'd use what I figure is my cost for the points.
I calculate my cost as
- Maintenance Fee's
- Lost interest on purchase price
- Depreciation
For one set of my points, that would be
$5.04 (maintenance fees)
$2.40 (3% lost interest on $80)
$2.00 (I bought 40 years for $80)
Total of $9.44. In reality, I'd probably end up charging either $9 or $10, depending upon how I was feeling towards that friend that day.