First you say "for a EMD with 15k searches" and then you say "5k searches". That is quite a considerable difference. Is it a one word domain? If yes the price would likely be very high. You ask how much you can earn from the domain the answer to that is rly complicated.
Is the domain ranked anywhere? If not then you probably cannot earn anything from the domain at all since the traffic would be very low. Unless again, if it is something that people might type domain.com into their browser, but those are premium domains that you should not even consider buying without experience as their prices are very high.
If it is not ranked anywhere and you are planning to rank it then it might be a better idea to buy a new domain instead of that one and build a brand. EMDs do not give that much of a boost anymore these days. Building a brand might be the smarter way for the long run.
In short its impossible to tell you a value without actually knowing a lot more about the keyword and domain as different niches also would have different prices.