A generic model walking foot would not come close to the Bernina quality. I tried one and they just aren't any good.
Watch ebay and you should be able to get an old style Bernina walking foot in the $40-50 range. The 830 is a 4mm feed dog width to the older ones that come in the plastic case would fit, although they don't have interchangable soles or a fitting for a quilting guide like later ones. Any that say that they are for 1630 and earlier would fit but later ones could be for 5.5mm feed dogs.