That is a very good price on the vpi setup. It should sound better than the mmf-7 without an upgrade. The mk-II is actually a better set-up than the jr., the only reason I can see that it would sell for less is maybe it has an older motor, but I can't see where that would conflict with any upgrades. The bearing should be the same as a jr. and mk-III, there have been bearing changes since the mk-II was discontinued, but the bearing would only set you back about 180$ (check the vpi website) if you wanted to go to mk-III (that would be as high as you could go before a bearing change would be nessesary).
BUT: the jr. platter is all acrylic, the mk-III is the same but with lead to make it heavier, The old mk-III used to be aluminum/lead/acrylic, and was discontinued for the lead/acrylic, which is obviously cheaper to make. The mk-II is similer to the older mk-III, It's just not as heavy. The point of all this about the platters is that to go higher than the mk-II to really be worth it, you would have to go past mk-III, so the older bearing won't hurt you. (unless you found a used mk-III platter, which would likely have an older bearing anyway).
The last time I saw a mk-II, it had a sprung suspension and a separate armbaord, as opposed to the jr.s' one piece mdf, that would make it cheaper to upgrade as well, IF you wanted to.
I haven't heard of the rb-1000, but my understanding of the rb-600 is that it is suppossed to be an updated rb-300, somewhere between the rb-300 and rb-900. I'll skip whatever innaccurate details I know for sure except to say the the new price for the rb-300 is $425, the 600 $695, the 900 $995, the comments by marakanetz still apply, because I think you should stop reading this and get on obtaining that turntable if it isn't already gone.
Please keep us updated as I am excited for you.