When you say handle sales, do you mean handle product development for each project that you have landed? So basically an account manager? Or do you mean someone that goes and lines up new sales? Just want to get specifics, so everybody understands what is being discussed.

Someone who manages what we promise to the client and how much they pay for it.

A huge part of the role is just deciding requirements. Whether this thing is possible, how much it costs, keeping the client from sneaking in something impossible, and lowering the costs to us when we can't deliver something that is too expensive to build.

The person has to be good at not overpromising things. Or managing client expectations.

Many clients prefer waterfall because it's easy to estimate project costs but it tends to be extremely costly to both parties. So someone who can educate the client in how to work from an agile perspective, suited to their budget restrictions.

There's the legal landmine to maneuver. What happens when things go wrong.

There are also many unethical people, especially in large companies, who are experts at pushing people into those landmines. They ask for impossible things then refuse to pay when those conditions are not met.

So the ideal person or service needs to be good at reading clients and avoiding these kinds of contracts.

You should check out Toptal / Gigster.