Everyday Source is offering a $20 voucher for $10 today courtesy of Groupon.
I will tell you now that these are typically sold out by the time I get up on the West Coast when they are offered (6-7am PST)- so do not wait to buy if you are interested!
Everyday Source has accessories for various electronic equipment but they also offer ink and toner! So you might score a great deal on ink.
You might have a look at the selection and prices before you buy. There is a limit of 1 per household with 3 additional as gifts. You also get free shipping!
Head over to Groupon here to purchase your voucher (Las Vegas).

I just got this for ink the other day! My recycled pack of color and black for HP was just $14.99 (it is $60 full price for me to buy new cartridges in b&w+color). I had a hard time finding a filler because you have to make a $20 purchase to use the Groupon, but to make it easier for everyone else, I found iPhone 3G cases for $2 and a stylus pen for a Cingular PDA for $1.29. The site is hard to navigate and I wasn’t able to find a way to search by price without having a specific item in mind. They also sell button cell batteries for $3.99 and Nintendo DS stylus pen packs for $2.99-3.99. Hope this helps someone else looking for a filler item to make it to $20!