Sono Elements has released eTron Pro, a Mellotron plugin emulation featuring 17 multi-sampled sounds of the classic instrument. Each sound can be modified using an amplitude ADSR, a tremolo, a lowpass filter, a simple reverb as well as a lofi noises engine.
Price: $29 USD.
eTron Pro is available as a VST, VST3 and AU instrument for both Windows (7, 8, 10) and macOS (High Sierra and up).