Thanks everybody. I ended up ordering it from Petco. They had it "on sale" and also had a deal going that if you spent more than $45.00 you got an additional 10% off, so that, along with the cheap shipping they had, made it the cheapest place to buy....at the moment...

One interesting side not. I called out local Petco and asked if they had it on the shelves (since sometimes I'm too impatient to wait for it to be delivered) and yes, they had it on the shelf. So I asked how much, and she said it was $25.00 for the refills and $40.00 for the plug-in! How can they be so cheap online and so expensive in the store?! So even though I have to wait for it to be delivered, I couldn't resist the savings.