I wouldn't recommend you to hire some random coders online or someone who will work for you remotely.
Exchanges are not a thing like a normal site or normal software, which you can rely on remote & random coders online.
Exchanges need huge security feature. You, as an owner, need to ensure that for your users. Exchanges are the biggest target of hackers nowadays.
I recommend building a strong team in your local place with an office. The team must have 2 or 3 security specialists to make sure your exchange is not vulnerable.
A normal crypto-to-crypto exchange.
2 security specialists means 200k/y, I don't get how all of those salary hours could be justified by a small-medium sized exchange, could you elaborate (if what you said is a result of what you know from experience)?
How about if I create a dex instead?