You can invest maybe $ 40- $ 50 for an inexpensive set of front & rear bags, a little over $ 100 for better quality leather bags and an inexpensive front rest like the Stoney Point, a bit over $ 500 for the same in top of the line Sinclair stuff, to nearly $ 900 for a
JJ Industries (front rest only). If you're not competing, the Stoney Point gear will work just fine.
Good quality, dry masonry sand works as well as anything. Bags need to be adequately filled, but not over-filled so that they "balloon" ... a dead-solid/"quiet" rest is what's required, not something that shifts/rolls around. Corncob or walnut media or plastic beads generally will not provide the type of support required.