Prices will vary depending on where you shop and in which country you live in. I will publish UK prices, if you want to convert them into dollars or other currency then use this link "Currency converter"
Ink cost per cartridge and complete set
Quantity of ink in cartridges and price per ml
The figures above are all based on manufactures recommended retail prices.
Although the Epson cartridges sound like they are the cheapest, the HP has over twice the capacity. I do not have print yield figures at this stage, but you could assume that the amount of ink placed on a sheet of photo media will be similar, i.e. I don't think any of them will use a significantly less amount.