I decided to sit down and work out the math. Here's a breakdown of the costs but keep in mind the cost can widely vary to some degree depending upon the brand of printers and the models and type of cartridges and type of refill kits to fit the specific models, for instance, my old printer Canon cartridges used to cost around $10 and alternative brands cartridges went for $3 but now my current printer black cartridge costs between roughly $20 or $25 depending upon who's selling it. Comparatively, such variables significantly alter the cost of ink per page including bulk ink prices depending upon the printer model. And your own method of working out the math may or may not differ from mine.
When I had first gotten my Canon multifunction PIXMA MP180 model last year I vaguely recall the Canon brand replacement black cartridge used to be priced at roughly $25 while the color cartridge was roughly $30 but I just checked again and they're now reduced priced at Canon for roughly $20Black [$19.99] and $25Color although most (but not all) alternative brands still sell them for roughly $25Black and $30Color. I've never refilled a completely empty cartridge but it's my guess that a black cartridge holds approximately somewhere between 10 to 12 cc's or ml's for roughly $20 and prints out around 170 pages before the ink starts running out and the pages begin to get only partially printed out. With this specific model in mind, 170pages/$20 congruent to 1page/n [where n is the cost of pennies per page], that is, 2000pennies x 1page divided by 170pages = 1page costing 12cents per page when using a $20 cartridge.
For the same price of roughly $20 the ?large? size starter refill kit for the PIXMA MP180 model from The Printer Ink Warehouse contains 120 ml's and does 7.5 refills. That's comparing 10 to 12 ml's for a roughly $20 cartridge, compared to 120 ml's for a roughly $20 [$19.95] starter kit. Math-wise, 170pages x 7.5refills = 1,275pages. 1,275pages/$20 congruent to 1page/n [where n is the number of cost of pennies per page], that is, 2000pennies x 1page divided by 1,275pages = 1page costing 1.6cents instead of the 12cents per page.
However, the X-large refill kit for $29 gives 250 ml's and does 15.6 refills which works out to 170pages x 15.6refills = 2,652 pages for $29. 2,652pages/$29 congruent to 1page/n [where n is the number of cost of pennies per page], that is, 2900pennies x 1page divided by 2,652pages = 1.1pennies per page with the 250ml's refill kit.
Refill kits from The Printer Ink Warehouse roughly costs $5 [$4.95]. If buying 250 ml's in bulk ink without a refill kit the price is reduced by roughly $5 or roughly a total of $24 instead of $29 for the 250 ml's which brings the cost down to 2400pennies x 1page divided by 2,652pages = .9 cents or 9 tenths of a penny per page. At this point and in this particular specific instance the cost of ink per page is reduced to a fraction of a penny per page. Keep in mind that the same amount of bulk ink have different prices for different models even within the same brand name printers. Bulk ink also comes in 500ml's, 1000ml's, and 1gallon sizes and of course the bigger the bulk the slightly bigger the savings.
Now that I've looked over these figures I can see where my old printer gave me a much better cost per page than my current printer does since cartridges and bulk ink prices are significantly more expensive with my current printer. It looks like I'm currently getting only around 2 pages per penny which is drastically far from the 50 to 100 pages per penny like I thought although it only feels like it because I had stopped worrying about the cost of ink altogether. I suppose if I lightened my printouts to get more prints per cartridge it would improve the cost a little but me thinks I'd be better off with a different printer that comes with less expensive cartridges and hence less expensive bulk ink prices?
To conclude, it appears actual cost in general is more realistically around a few to several pages per penny for most people when using bulk ink, that's my guess but I suppose some people could perhaps get 10 or more pages per penny? Or maybe my math is off? Each individual would have to visit The Printer Ink Warehouse for themselves to calculate their own numbers to see how much of a fraction of a penny per page it would be for their own printer model but never-the-less the fact still remains, refill kit and bulk ink is thee most economical way to go in terms of PAGES-per-penny which makes sense and only logical when I think about it.