Swanson Vitamins is probably the best  price, and excellent quality. L 
Why not use Daddybobs magnesium mix? Cheap and I even make coffee, lemon  
juice drink and tea with it. 
Jigger of Milk of Magnesia
liter of club soda chilled
shake for 30 seconds then refrigerate for 30 minutes
shake again for 30 seconds and refrigerate
Use 1/2 cup of this mix to one pitcher of water
I have been using this mix for my magnesium. Daddybob said you can use  it 
to your bowel tolerance. I have used up to 2 quarts a day and have not  
reached bowel tolerance.
I have high uric acid and get gout when I forget to take magnesium.
Brickey