Money issues aside, here's my opinion. The S90 is the way to go. Motif sounds(better), better piano sample, better action and ultimately more support. Many S80 users are upgrading to the S90. As good as the S80 is, the S90 is better. The S08 should be your last option. I wouldn't be surprised if many of the S80's that are for sale are because the owners want to upgrade to a S90. Usually the upgrade from one model to the next isn't significant, but in this case it is. Ultimately the decision is yours, but most people will buy a synth for the quality of the sounds, this is where the S90 really shines. If you haven't , go listen to one for yourself. It will blow you away!