Im a vampiire and to get a cure I need 5 empty grand soul gems how do ..

The single best place to find empty Grand Soul Gems is the from the Mystic Emporium, located in the Imperial City Marketplace District. If you have a copy that has the duplication multiplier glitch, just dupe the one you bought.

If you don't know if it does, then pick a scroll you have more than three (3) of, drop one (1), equip the scroll you just dropped one (1) of, and go to the Grand Soul Gem in your inventory and drop it, then back out of your inventory, and you should have four (4) Grand Soul Gems now, one (1) for each copy of the scroll equipped and the original one (1) you dropped, repeat as needed for any item you need more of.

If you can't dupe them then you'll have to buy them one at a time, wait 24 (twenty-four) hours and check to see if the shopkeeper has restocked it yet, continue waiting and checking until you have the needed amount.

Duping items is also a fast way to earn gold, get shopkeepers to like you (and thus get shopkeepers to allow a higher percentage in haggling), up your Mercantile level, and up your speechcraft level. This is also a good way to up your Alchemy level by duping potion ingredients and mixing them. I suggest Feather Weight and Health potions, you can drink or sell the weaker ones but drinking them helps to raise your Alchemy level as well.

!!!!!WARNING!!!!! Duping items in large quantities can lead to SERIOUS lag time until the duped items have finished generating and (sometimes) put in your inventory, the best place to dupe is the Talos Temple in the Temple District.