Tulving is known for their low cost, but they have high minimums. They deal in minimums of 20 ounces of gold and 500 ounces of silver.
Peter Schiff is pretty well respected around here. His Europac metals company deals in $10,000 minimums.
Gainesville Coins and Provident Metals are well known internet dealers with no minimums.
For small purchases, you are often better off heading to your local coin shop and saving on shipping.
We all want progress, but if you're on the wrong road, progress means doing an about-turn and walking back to the right road; in that case, the man who turns back soonest is the most progressive.
-C. S. Lewis