David VanDyke said:
If you find someone on Fiverr that will "translate" your book for cheaper than proofreading, they will almost certainly not give you a good product. In fact, they will likely run your text through a machine translator and hand it back to you after collecting your money.
Not always so. I used an English to Brazil Portuguese translator from fiverr for 3 short stories. My wife has qualifications in literature and language in Braziil Portuguese and proof read them. They were fine except for one obscure slang word, but she did point it out. Though I will agree there is a risk unless they have been on there some time and accumulated many recommends. As the name implies, you won't get one done for a fiver. What you have to remember is the exchange rates and average wages in different countries which can enable some translators (not all) to offer lower prices to be certain of regular work.
The cheapst ones in South America don't advertise their services. I worked at an English language school and some of the other teachers translated work to English in their spare time, mostly University papers, then gave them to me to proof. They charged peanuts. (and paid me peanuuts, lol) Whereas those in business as the other end of the scale for such as legal docs, charged just as much as in Europe.
As an example, someone in Brazil would be considered rich if they earned 100,000 br reals per year( $18,000), with the minimum wage there at around 12,000 br reals ($2,181.) In Brazil royaty % are prescribed in law besides the original fee, but with those earnings and a low original fee, I wouldn't begrudge them earning a royalty. In practice though, many don't ask for the royalty, but make no mistake if you became a bestseller, there would be a knock on your door as Harper Collins found out with the translation for Lord of the Rings, even for the film company and the sub-titles, used from the translation sold to them by Harper Collins. They used their standard work for hire copyright waiver contract, but it was defeated in Brazil in the courts, some of it settled out of court.
As for the US, unless it's changed and you contract for "work for hire", to include all rights to market as a book free of royalties to the translator, you'll be fine. In other words, you can contract with the translator to waive what would be their rights to claims of copyright.
Most countries you can't contract out of translator's moral rights if they have signed up to the Berne Convention for translated derivative works, and in some counties, royaties are enshrined in law in addition to other rights. It's down to where the translator resides (not where the author lives or the the language type) and you doing your research on translation rights in law for that particular country where they reside,
In practice, most rights are not to make changes to the translation without permission of the transator, and to name them as the translator. Sayng that, there is always the thorny issue of other rights that could make things complicated for such as film, or say audio rights for the translation, etc
It's not as simple as asking how much does it cost. Take China as an example. Last time I looked Chinese translators contracts last for two years in law, even for work as an employee within a company, then ater the translator can do as they wish with the translation, including to compete.