Hey Tee,
I'm sure no one here has their noses that high in the air. The fact that you even KNOW about Mellotrons, and want one, is the Awareness we all want to foster, anyway. It was a number of years after I'd learned what Mellotrons REALLY could do (The Beatles, definitely, but King Crimson #1 was the one that really dropped MY jaw, & I know I'm not alone there!), before the planets lined up & I was able to find a super-clean, used M400, around 1976. I later ordered custom tapes for a 2nd frame, & to customize the originals VERY slightly, adding tymps & percussion to the lowest 3 keys. It literally DID change my life, no doubt.
A couple of years ago I played the M4000D as mentioned below, & it's a magnificent instrument. Still a bit pricey, but it actually brings you 100 (or more) of the sounds available in the Mellotron library. Obviously, more details could be had for the asking. Lots of online stuff about it. Further, the 4000D shows pictures of the 'Trons you're using, so it adds a hint of warm fuzziness, anyway. And you can pick it up under your arm & take it anywhere... something a LITTLE tougher with a full-size instrument.
True, most people are so used to samplers & plug-ins, etc, that none of them have the "panache" or mystique of a real, "open-the-lid-&-show-people-the-tapes" Mellotron, but the M4000D is an awesome, well-sanctioned starting point, with no "euphemistic" or suggestive name on it! In fact, I'm sure LOTS of us would like one to take out for easier stage use.
There are many who ask "Why a Mellotron, even a 4000D, instead of M-tron Pro?", etc. well, there ARE differences, in how they play, & yes, how they sound. (I have M-tron Pro, too, so I speak from 'sperience). Even just to use the volume pedal - not possible with software - is a HUGE part of playing Mellotron, which the 4000D does allow. And if you ever did go live, to hook up a whole computer system, keyboard, etc, to play your M-tron, may end up being less reliable than an old, crotchety, out-of-sorts 400 with dirty tapes! (-:
Good luck to you!
Cheers,
Berington