Yes, the ink factor makes the 3800 a bargain, if you do a lot of printing.
According to Eric Chan 3800 FAQ (http://people.csail.mit.edu/ericchan/dp/Epson3800/faq.html#inkcost
) a sq foot of paper uses about 2ml of ink (total from all cartridges, some much more than others, and others much less depending on the subject matter)
At 80ml/cart, you have 720 ml to start, which in total will print about 360 square feet (or borderless A3=1.4SF= 257 prints or borderless A4= .67SF=1080 prints, etc). You can do the math to see how much you will use in a year or two. In short, the 3800 is designed for a "medium" frequency printer.
Also, in Eric's FAQ is the following:
"Once you install an ink cartridge, Epson recommends that you use it up within 6 months. This is to ensure consistency and color accuracy. However, owners of other Epson UltraChrome K3 printers (e.g., the R2400, 4800, 7800, and 9800) have found through experience that it is fine to continue to use ink cartridges much longer than the recommended 6-month period. Many users have reported using a single ink cartridge for considerably longer than a year with no perceived decrease in print quality or other ill effects."
Remember, that if several low usage carts give you problems, it's $50 per cart to replace, whereas the 2880's smaller carts are about $12 to replace, which will probably never happen unless they run out of ink!
It's too bad Epson didn't upsize the 2880 carts to maybe twice the current size - HP offers XL consumer carts that have 50% more ink in the same size cart, but, they would probably not make as much $$$.