I'd say go for a Mopho keyboard used (i got mine for $500) or if you have to have a juno, get the 6 as it'll be cheaper and more reliable than the 106 AND it'll sound much better, plus it has an arpeggiator. I picked one up recently for $325, for example. Other good cheap synths are Alesis ION, Jp8000, Arturia Minibrute (it's the closest thing to my modular for the sonic capabilities), and as people stated, moog is launching a new synth and rumors state that korg may as well. I'd say honestly wait till after NAMM because either you'll find something you want or other people will and the used market will probably be flooded with stuff to buy if the new stuff is either too expensive or not as interesting to you.
The main reason to get a juno is for those classic house basslines, chord memory stabs, etc. That is until you have some gear that outputs CV and THEN it's a bit different. I have my Juno 6 paired with a Moog cp251 unit that has an lfo, mixer, sample and hold, etc and I use that to mess with the arp clock and filter cutoff and it really opens things up.