Beyond Belief ???????????? aka.......a trip to Office Depot

A few weeks ago my printer got terminally ill and I was forced to issue a DNR on it.  The following day it was buried in the trash room in my building.  Because of this wonderful economy and trying to save money wherever and whenever possible, I purchased an all in one hp office jet at Costco which was priced really well.  I was so happy that I got a new printer/fax/copier for a cost pretty much the same as a new printer cartridge.
     What bothers me about this whole thing is that I never look for bargains.  I have always felt that you get what you pay for.  There are no shortcuts, there are no secrets, there are no hidden shortcuts, there is nothing but truth in that statement.  OK, so I am pretty good with computers and figured out how to work this dumb thing as everything needs to be done from the computer screen as the controls on the printer are really there for show.  Naturally at this point the Costco receipt is long gone, along with the box etc.......to late to return it..... OK, I can live with this........Yesterday, I went to Walgreens to have the ink jet re-filled because it is only $9.99 there.  Yup, your right........This particular cartridge cannot be filled at Walgreens.  They only do the other 999 ones that HP make, not this one..........OK once again, I can live with this also.
     Today I began my journey to my local Office Depot where they have everything.  I look on line first and find a coupon for $10.00 off a $30 purchase.  I am happy and know I will be in and out of the store with my new cartridge set (black and color) in a few minutes and have saved $10.00 along the way.......Now.....this is what I thought and of course not what happened.
      I got inside the store and easily found the number HP cartridge set that I needed.  That took maybe 19 seconds. I was on a roll now and off to checkout.  There are roughly 6 checkout counters but naturally only one is open with a post office reject standing there pointing her scanner at me like it was a tazer gun and  I was about to get it. She scanned the cartridge pack and the $44.00 price came up fine.  Then she scanned the coupon and of course that would not work.  Don't ever try to reason with one of these lunatics because you will not win.  OK, I am not going to get angry. Why??? Because I see a big sign at the counter that says "Simply give us your e mail address and save $10.00. "  That is simple enough and I do that.  Now, Tazer lady with her tazer gun still pointing at me advises me that it is for your next purchase and only good when spending $50.00.  Nowhere on this sheet that I filled out , was that printed.
     At this point I am now thinking to myself that I understand why people go nuts and start killing everyone around them.  Naturally I would never consider doing something like that, however, I would really like to tazer some of these checkout clerks in different retail chains around here.  My luck, they would not accept my coupon to purchase a tazer gun.