That particular Samsung vacuum was VERY popular here in Canada, & bags should be easily obtained from most any vac shop. The Bissell Digipro bags look like they would work fine as well. Both the VP-90 bags & Digipro bags are available on Amazon.com & looks to be fairly common on online vendors.
If you wanted to substitute bags, though, you could try a Panasonic C-18 bag, JohnnyVac Hydrogen bag, or Miele FJM bag. The hole on the bag collar looks nearly the same, as well as being pretty close to the same size. You would have to remove the bag holder in the canister & mount the bag DIRECTLY on the tube on the bag door, & possibly wrap the tube with a little clear parcelling tape that can be obtained at most dollar stores, to make the bag fit a little more snug on the tube. Both these bags are made of HEPA Cloth, whereas the Samsung & Bissell bags aren't, so it might be worthwhile if you want the better filtration, & unfortunately Samsung didn't use the best quality HEPA filters on the exhaust of these canisters.
Rob