[Qetzal]

Originally Posted by madinmelbourne

I have two sized items with different prices which I've added successfully, what price do I then put in the main price box? When I leave it blank obviously the product shows $0.00, when I put the lowest price in and buy an item, the price doubles.

Product options don't set a new price. They add a markup to your base price.
For example if you have two options, the first one costs $10, the second one costs $15

Set the base price to $10. Then the first option will not change the base price. The second one will add $5 markup.