So I live in a pretty small town, but there are two post offices in my zipcode, about 8 miles apart from each other.  One is closer to my house, but the one further away is where I stop by when I'm running errands and whatnot.  I mailed two different books this week, each paperback was about the same size.  On Saturday, it cost me $3.09 to mail first class, from the PO near my house.  On Tuesday, the price dropped to the expected $2.41, mailed from the PO further away.  Both books were being mailed to about comparable distance.  But it really got me wondering - was I being overcharged because of an incompetant clerk, is postage somehow MORE on a Saturday, or do I just have really awful luck when I go in person?!?!  I would much rather pay a few extra cents to mail a book that gets to its destination faster, than pay the media mail rate and have a book take FOREVER to get there. 

But this experience got me thinking, has anyone else out there experienced this when mailing out books?  I know I should just pay for my postage online when I print out the book wrappers, but I'm just not comfortable doing that yet for some odd reason. 

I'm curious - does anyone else have any thoughts on this?  (Please be nice!  I honestly started this topic just to chat!)

No, but sometimes you need to tell them that it needs to go media mail. Did the book that was charged $3.09 have first class marked on the package or media mail?

Gaby, distance traveled is not a factor for Media Mail (or First Class).  Media Mail rates are only calculated on weight, so if your books weighed the same the postage should have been identical. 

Took me a while to digest this.

My guess as to what happened is this:
_______The first book (at the nearer PO) weighed in at 12oz (that's a postage of $3.09 for first-class as you said).
_______The second book (at the distant PO) weighed in at 8oz (that's a postage of $2.41 for first-class again).

First off, you would have saved money in both of these cases by mailing it Media Mail.  You will need to ask for media mail (the employees won't suggest it, as it is the cheapest rate available for regular people and so effectively loses USPS money).  The only exception I know to this suggestion may be if you are in Wisconsin (and that is a whole other long story).  An explanation of media mail and what can be sent in this fashion (the contents are specified) can be found here, but all books sent using PBS rules will be acceptable.  For both of your books they would have mailed at $2.38 using Media Mail.  When you go in tell them you want to send the books Media Mail unless 1st Class is cheaper (only true if the books weigh 7oz or less).

As for the time it takes, I've noticed that it took longer over the holidays, but in general when I've used this rate (which I've used for a while although not with as much knowedge about it as I have now), it really didn't take any longer than 1st-Class.  Neither of these have guaranteed delivery times or anything.  Then again I'm the type of person that misses being able to order something with the option of 6-8 week delivery (for next to nothing on s/h) which you can't find anymore.

As for the difference in amounts there are few possibilities I can think of.  It could be that one or both of the post office scales haven't been calibrated recently (not sure of the standards on this for USPS?).  4 oz isn't that much of a difference so it is possible that the books (especially counting the wrapping) simply weighed that much of a difference.

Hope that helps.

EDIT: Checked out your locale, I miss being asked red or green.

Thanks to everyone for replying!!!  Lots of great perspectives and mailing advice/ideas.

Rachel B:  I paid to send both books first class (really, the difference should have only been about 9 cents from my calculations), and the more expensive postage was indeed labeled first class (and it already was received, phew!). 

Trucker-Monkey: Red or green is definitely something one misses when away from NM.  That, and being able to order green chili burgers practically everywhere!