MER capable signal generator

Hi, anybody can advise an MER capable sig gen, in IF levels only; and is it possible to have it as simple and cheap as possible? (like a single pwa 2-tone siggen, but this time, MER capable). Thanks!

Because MER is direct proportional to EVM check also for this option.
I don't think is a cheap vector SG on the market. Usually the price starts from 20k and up.