I get the coarse discs for grinding from ebay there's a seller with some which work well in packs of 10 and 25, search for Abracs PSA. There are grits from 60g to 320g, as I said good for the rougher work only. You have to make your own centre hole but I just stick them on the glass disc, put a stanley knife in the middle and use the hole in the glass to guide the knife.
I find I use these a fair amount when I'm rejuvenating some old ebay chisel or if I decide to change the primary bevel.
There's another company who stock the branded discs in the UK, the fine pack (400g & 1000g) is 12.41 as is the honing pack, still expensive for a few bits of sandpaper but a lot cheaper than Rutlands. They have stock currently.
I use the fine pack for polishing backs (pretty much a one off task) and initial creation of a secondary bevel, they last ages so long as you worked through the rougher grits properly first. I don't use the honing discs as I prefer to do that by hand, more control and quicker for renewing the edge while you're working.
I bought my worksharp about a year ago and have regularly checked Rutlands over that time, they often go out of stock of various W/S items, I bought the wide blade platform from them and it took 3 or 4 weeks to arrive. Maybe they only order it when they run out?
Other people have found other alternatives that are more affordable than Rutlands / Worksharp branded paper, see this thread from last week.
worksharp-disc-sources-t66762.html