The following might be stating the obvious, but here goes.
Bells - I like a nice low tone but they are $500 - $11,000 so I have been using a lovely stainless steel mixing bowl (14 inches in diameter, 6 inches deep) cost $5 US at the charity shop. For the striker, I have a stick (about 5/8 inch in diameter but most any diameter bigger than that will do) the end of which I covered in velveteen for about 2 inches (I sewed it on but you can glue it). When shopping for your frugal bell, try lots of bowls as even bowls of approximately the same size will sound very different. You hold the bowl at face-height, supporting it underneath on your fingertips, then strike the bowl near the top edge with your knuckle. If you have never tried this, the sound can be amazing. Of course, if, when using your bowl bell, you set it on the floor, the sound will not be so loud, so I would search for a bell that is very loud and resonant when you test it. A note on setting it on the floor, a firm but not hard surface is needed, I think, I am fortunate that my very low-pile carpet works fine.
Zafus - a few sewing notes for non-sewers - it is very easy to hand-sew a zafu - it is just 2 circles and a long straight piece that is pleated (folded on itself) and sewn to the edges of the circles. I recommend what we call skirt-weight fabric, heavier than cotton shirt material or heavier than bed linens. Again, your charity/thrift shop can be a resource since both the circles and the side piece can be "pieced" for two pieces of fabric. If you are buying new, perhaps ask for "cotton duck" or a similar weight or a medium weight denim. New fabric will feel stiff but will (if it's all cotton or mostly cotton) soften when you wash it. You should wash your fabric, dry it, iron it flat (if you have an iron), then sew. The choice of thread is very important. Do not use "all-purpose thread" (this is too weak for hand sewing a zafu because the seams will be getting a lot of stress when stuffed and you sit on it). Use what is called "carpet/buttonhole twist" thread. You will then probably need a slightly larger than normal needle. When hand sewing, every two inches make a "knot" but making a little stick in place and then running your needle through the loop. This makes a knot that, in case the seam comes open, then the seam will only open for two inches (so you only need to resew it for two inches). I would make the stitches no larger than 1/4 inch long and I would sew about a 1/2 inch from the edge. Then do a second row of stitching between the first line of stitches and the edge of the fabric. Stuffing - you can try the stuffing from old pillows, old clothes, tee-shirts also make great stuffing, and of course the above mentioned popcorn for that firm beanbag effect.
I will later post easy and cheap oriyoki set suggestions if anhyone is interested.
I have no idea if the above is of any use?