Five years for an e-reader? I'd be satisfied with two and delighted with three.
I also like Ficbot's "Total Ownership Cost" because it does help put in perspective the tradeoffs we can make in our discretionary "entertainment" spend.
I've only had a Kindle for six months, bought relatively few books, and consumed a few dozen. Currently my TOC would be around $15 per book read.
On the other hand, an HDTV plus 40 or 50 Blu-ray discs ...
ouch. I'd hate to calculate
that TOC! Oh, and if you factor in the cost of cable and HBO ...