I have been working on a website. I have two demo products for now :-
Now I added Custom Options for Sizes Available. There are two sizes :- Gallon & Cart and gave prices so it appears as + (amount) and adds to the total price.
Now the problem is when I click on the custom option in the product page the price does not gets updated instead it becomes zero.
I checked the link you provided and see that most likely you have already fixed the issue, as the price is changing depending on the custom option chosen. In case you have any other issue with custom options, let me know.
For other forum users who encounter the same issue I offer to set Price to Fixed and do not forget to indicate the value.
Also I suppose that further when you will multiply your products and you will face the issue, that you need to add custom options one-by-one.
To add them in bulk, you can use Store Manager for Magento application. Using it you will be able to create products and then clone custom option (in case you have the same custom options for products) or use Import/Export of custom options. As I know default import mthod does not have such functionality.