It seems as though PagePlus has given their airtime cards a few more minutes. The $25 card is now 200 minutes (up from 150), the $10 card is a minute more (71), and the $50 card has 25 more minutes (425 total). Considering the monthly fee and saying that you used the card for the full 4 months (thus $2 in monthly fees) here's the math:
$10 card -> 56 minutes -> 17.85 cents a minute
$25 card -> 184 minutes -> 13.6 cents a minute
$50 card -> 408 minutes -> 12.25 cents a minute
$80 card -> 780 minutes -> 10.25 cents a minute
All in all the per-minute rates aren't that bad, but CheapPhoneCards doesn't seem to carry them any more. Keep on the lookout for someone who does and gives a discount while doing so, then email me so I can put that info here.