I agree that the Canon Pro-100 is an excellent printer for many papers, including more varieties than you'd expect. Prints on baryta papers can look excellent. Prints on Canon Premium Matte (PM-101) can look considerably better than you'd expect.
In the U.S. at least, the Pro-100 is a bargain. Last I checked, the cheapest real deal was at Adorama, $119 net of rebate with a full (or slightly more-than-full) set of inks, 50 - 13x19 sheets (semi-gloss or luster), 10 - 8.5x11 sheets (luster), and free shipping. But within the last year there have been deals for half that amount.
[D]o you have a feel for the on-going cost of ink per print of X dimensions?
As some (maybe most) of you know, Red River Paper ran a test (
http://www.redrivercatalog.com/cost-of-inkjet-printing-canon-pro-100.html). Their reported costs are actually conservative for prevailing U.S. ink prices. They used 10.29 'cartridge equivalent units' to print 200, 8x10 inch prints (of Bill Atkinson's printer test page). At prices I've actually paid for sets of CLI-42 ink within the last year, that works out to somewhere between $0.66 to $0.77 of ink per 8x10 inch print (Red River reports $0.875, using $16.99 cartridges--I've never paid that much). Because of the mixed use our Pro-100 gets (not all prints are photo prints, and not all photo prints are full coverage), I can't give you very relevant stats; but my sense is that Red River is about right. If you use Canon's better but not really high-end papers (e.g., Glossy II or Pro Luster), they cost about $0.32 each for letter-size (B&H prices at last order). So an 8x10 inch print on letter-size paper costs about $0.98 to $1.09.
Also as some (maybe most) of you know, these Canon printers use ink for automatic self-cleanings, especially if nothing is printed for several days or weeks (reportedly there are different levels of cleaning
triggered when a new print is made at intervals from 60+ to 480+ hours). How often you print determines what fraction of your ink gets used on self-cleanings. I have 'measured' (using Canon's driver-based ink-level reporting) the ink used, and even the heaviest cleaning (i.e., after 20 days) appears to use less than 0.5 ml per cartridge (how much less I won't be able to tell until I have more data). On the other hand, if you make a couple of prints, wait a week, make a couple more prints, wait a week, repeat, it would not shock me if ultimately half of your ink gets used in self-cleanings.
So accounting for ink used to print, ink used for automatic self-cleanings, and paper, IMO a reasonable estimate is somewhere from $0.98 to $1.86 per 8x10 inch print. Obviously YMMV!