Sound Box for the Elektron Analog Keys/Four has 128 sounds for $19 over at www.newwavepresets.com
If you want to add more sounds to your Elektron Analog Keys or Elektron Analog Four you could do a lot worse than consider this pack. But don't take my word for it. Take a listen to sounds from Sound Box on the New Wave Presets website.
Sound Box includes classic sounds like emulations of vintage synths, and acoustic instruments, and also new unheard of sounds. You will discover various basses, leads, keys, drums, FX’s, and a nice selection of pads and atmospheres. There are 128 sounds packaged into 1 .syx file for the Elektron Analog Keys/Four.
For analog Keys users many sounds make use of the modulation joystick, velocity, and aftertouch.