The general procedure with Staples.com is to call and ask for a deal until someone tells you 'Yes.'
Here's some pointers on accomplishing the deal you desire:
*Note: If at any time during these procedures, someone tells you no, tell them thanks and hangup. Then call back and speak with someone else--make sure to write down EVERYONES name that you speak with to avoid them realizing that your calling over and over again.
1. The PM policy DID change, such that you can't PM and use coupons at the same time, but that doesn't matter. Make your order, PM it to the lowest possible price... then tell them that you have to leave for an appointment (be creative here) and to place your order on hold. Then call back in an hour or so and bring up the order number. Then tell them you decided not to add on any items and apply the coupon code--they have never noticed the fact that the item has been previously PM'ed. This is sure fire!
2. This should be obvious, but if you're planning on buying a lot of merchandise, it is beneficial to break it up into smaller orders and then apply the appropriate coupon codes.
3. Think about how you can get more for your money. Case in point: I watned to purchase a SB Audigy X-Gamer from Staples.com (now, some of you will say, "Staples.com only sells the Audigy MP3, what gives?" More on this in a moment...). The price of the X-Gamer was $99.99. Most people would buy some paper clips to push the total over $100, then use the $25 off $100 coupon for a price of $75. The way I did it was to PM the Audigy down to $65, then purchase $35 worth of office supplies that I needed anyway to push the total up to $100, then use the coupon to take it back down to $75. So I ended up with about $135 worth of Staples.com merchandise for $75! This deal was sweetend by the fact that I PM'ed the Audigy X-Gamer to the Audigy OEM... which brings me to my next point...
4. This one is only for the very patient (and slightly unethical) person. It is very possible to PM a Staples.com item to a different item, as long as they are similar. Let's face it, Staples.com CSRs are not the brightest people and don't know the difference between Audigy X-Gamer and Audigy OEM... all they look for is the word "Audigy." The same goes for Kingston 512MB PC100 RAM and Kingston 512MB PC2100 RAM. Slipping this kind of thing by them takes skill, patience, talking to A LOT of CSRs, and mostly luck. I have only pulled it off once, but I usually give it a couple shots. (Don't bother to flame me about this, if you have a moral objection, I understand... I should too.
5. Finally, (this point is the holy grail in terms of cheap components from Staples.com) I'd like to point out that Staples.com inventory is pretty limited when it comes to computer components. However, through some investigation and trial/error I have found that Staples.com has a vendor called Ingram Micro. Ingram Micro (IM) is huge and carry tons of components. It is possible to call Staples and ask them to do a 3-way call to IM, then you can check on the availability of any item you wish. The prices will be outrageous, but then you can always PM and coupon code your way down to a good price. Using this method you can usually get very popular items, from a good vendor (Staples.com), for $30 less than anywhere on the internet. I have purchased a Plextor 16X CD-RW drive, an Audigy X-Gamer and 1 GB of Kingston DDR with this method.
I always buy from Staples unless IM doesn't carry the item I want, then its back to Newegg. Also, be aware that Staples.com often offers free items with $x.xx purchase (like the free backpack with a $25 purchase). You might as well get this and sell it on Ebay to bring in some more money... or hope that they don't have the back pack in stock and then they'll give you $60 (value of backpack) off of your order.
This, my friends, is all I know about how to save money from, and swindle, Staples.com. Try some things out and see if you like it. Oh, and one final note: They can't PM items that's aren't on their webpage. It has been my experience that they look in their web-database about half the time, the other half of the time they look things up in their "AS400" system. (you can tell when they're looking on the webpage because they'll ask for your zip code) This is important since none of the items that you special order from Ingram Micro will be on their webpage. Just tell them to look it up in their AS400 system, at which point they will be amazed that you know so much about their ordering system, and possibly so stunned that you'll seem to be authoritative, which always helps when pulling off a good deal.

And like always, if they say no for any reason, write down their name and call back!
Oooh, almost forgot! When you call, they'll open a new order form and ask for your info. Ask them if you can check on the "availability and pricing" of an item before doing all the technicalities. Once you have gotten them to give you the desired price, then give them your info... otherwise there will be a record of your order, the failed PM attempt, and the order being canceled. I learned this the hard way... I called back once after calling about 5 previous times (and giving them my info) and the CSR said, "Why is there 5 canceled orders for this same item all from today?" Needless to say, I couldn't get the deal because he realized what was up. I waited a few days and called back... anonymous until the end... good to go!
