I honestly have no experience with warehousing and fulfillment, but the inner hacker in me loves to think of cool applications for barcode scanners, sensors, some nifty Arduino/RFID projects, reporting and even "Smart Promo Distribution" where you could warned that the ZIP code you're about to send that Red Lobster gift card doesn't have a Red Lobster location within 50 miles

You're right through...cool hacks aside, the physical act of retrieving an item from inventory, packaging, labeling and shipping has its own drawbacks.

Storage fees are fair, I think. Think of the value: before even paying the cost to the carrier (USPS/UPS/FedEx) you've invested time and money in to that label printer that never works right, consumables such as ink/paper/packaging, your time packing these promotional items and God forbid you run out to get coffee when the UPS guy swings around to pick up!

On a small, manageable scale, it sounds like an awesome operation for a programmer/tinkerer.