The one thing about plugins is that you can often find emulation of the most expensive instruments in the world, for a fraction of the price. The Mellotron MKII was introduced in 1964 and aimed at the home market. It was two manual and featured rhythm sets and accompaniment tapes on the left hand...coupled with lead sounds on the right. Used notably by King Crimson, The Beatles, The Moody Blues, Tony Banks and Genesis, The Move and many more...it was a machine aimed at the home market to compete with the organs that featured rhythms.
I have been lucky enough to be involved with Dave and Chris at G Force Software in the latter stages of the testing of the MKII and have done some demos for it. Keep an eye out for them on the G Force software website www.gforcesoftware.com and on their Facebook Page.