Language of diplomacy

This is too expensive.

(unfortunately/ would)

We're not interested in your economy model.

(would/ less)

It will be difficult to sell the idea to my boss.

(unfortunately/ may/ very easy)

We can't pay straight away.

(afraid/ might not/ able)

I won't make any promises.

(not/ position/ this stage)

We hoped you would provide after-sales service.

(honest/ hoping)

A fixed interest rate would be a good idea.

(wouldn't/ better?)