Don't know if anyone is still reading this thread, but another thing to consider is if your 830 has the hi/low gear option. This is a little white switch found just below and to the right of the feed dog knob, on the base of the machine. Switching the machine into low gear gives it something like 10X the penetrating power (or was it 30X?) which makes it wonderful for sewing hems on jeans over those thick outseams. If your machine has that switch it's worth more.