Ask a translator, if you want to, but I’ll answer some questions I was asked so far, anyway.
Q: What is a fair price for translation/review?
A: A fair price for translation, review and everything in between is the one that, after taxes, leaves a professional linguist with enough money for their basic needs, software and hardware they need for translation, repaying potential student loans, as well as vacations. Not less than you would pay your plumber or hairdresser for the same time they spent working for you, anyway.
Q: What are the best metrics for translation projects?
A: It depends on multiple factors. The number of words is pretty accurate for translation, whereas reviews, proofreading, copy editing are best priced by the hour or per project. For reference, depending on the language, 1 page has 250-300 words, it takes roughly 1 hour for translation, if you’re familiar with that specific field, or more if you need to research highly specialised terminology. Review, proofreading, copy editing depend very much on the quality of the translation and, therefore, I prefer to quote per hour or per project.
Q: How expensive are translations?
A: I don’t know how expensive is too expensive for you, but I know from personal experience how expensive cheap translations are: give me back my money expensive when you need them retranslated for a client, or job opportunity lost expensive, because you’re a psycho on your special ed diploma and now need a new translation, lives potentially lost expensive when your translator failed to understand that sparks and flammable gases don’t mix well. Cheap translations are rarely cheap. Most often than not, a cheap, bad translation you think you can re-use will need to be fully replaced and cost you more than it would have if you went for the reasonably priced option.