Hello,
Alexa rank, is a traffic monitor, has no real value.
I see that you don't actually get PR, you are buying PR1, good for you but if you want to get PR4+ you have to buy PR4+ link !, pr 1 is useless in this situation. I'm not talking about domain PR, you have to get a link on a PR Page !
Google makes sporadig updates for PR, the last one was 2 months ago, but the penultimate updates was made 10 months ago. They did one every 6 months, but now you'll never know.
Have fun buying PR 1 links.
Best regards,
Cosmin.