Some review sites make a point of carrying this information. trustedreviews.com does, like this for instance, though you will need to find one local to your currency or still do some extra research on part prices yourself. Actually, even if you do find such a site with your local prices, it is always worth checking what the actual retail prices (and availability) are like as they can differ from the official RRP (which is what review sites are likely to quote) enough to make quite a difference to your costings.
You can usually get this data from the manufacturer's sites too.
I don't know of any site that offers an easily accessed database like you are looking for. Such a site might be difficult to run because as soon as it showed one manufacturer to be better than another they'd bit hit with a lawyers letter suggesting that using the product and pricing information that way is a breach of copyright or some such (while such use is legally fine in most jurisdictions, arguing the point against a major manufacturer's legal team would be too expensive, time consuming and stressful for most to deal with).
Calculating your expected pages-per-consumable figures can be quite complex too as it depends on your actual output. Most official per-page figures for toner assume ~5% coverage without giving an example of what 5% actually looks like - I used to be under the impression that this was approximately a full page of text in a common font at a common size, though some articles I've seen (like this for example) suggest it is closer to half a page. If you are printing charts and such then the coverage will increase considerably, and for photos it will be even higher. So all you can really hope for without much study is a good view of comparative consumables costs, which will not be easy to compare against the fixed costs of buying the printers in the first place.