Prices management

Hello everyone. I'm having problems with the management of prices. I am French so I'll try to be understandable. :o

I'm on a proposed sale of photo. On my website, I sell photo with 3 different sizes. And each size has a price. (the picture does not affect the price, only size matters). I want in the selection of the size of the photo, that the price change and when you add to cart the right price displayed.

It's been four days that I do all the forums or possible test and I still have not found the solution. :shock:

My question is not very complicated, is it possible with isotope? I despair ... :(

I hope you understood my English ^ ^ :roll:

I think this is possible using variants. Did you set that up?

I just found it there was 1 hours !

If someone is having the same problem, MP me i'll explain him :)