i need to purchase vac bags for a compact canister vac sharl model # cv520b?

If you mean Sharp canister vacuum, I purchase my bags from
www.abcvacuumwarehouse.com they offer bags and belts for most vacuums at a better price than I have found anywhere.
Range Bags

Compact Camera Case_e2_Camera Mini Bag_Peach Red

$37.95

Compact Camera Case_e2_Camera Mini [...]