Sorting by price modified by combination problem

[martin.eu]

Hi,

I have products with several combinations (cloths - sizes) with impact on price. I decided to set basic retail price to 0, so prices are set by combination only (maybe there is a better solution, but i found this easy to update and manage prices)

Problem is with sorting in product list, when customer clicks category and selects "Sort by - Price:lowest first", it doesn't sort (because of basic retail price is 0 ?). How does this sort feature work ? Does it counts with impact of the combinations ?

If for example there is a product with three combinations, basic version is sold out and available are only versions with price increased by combination, what price will be a value used by sorting engine ?

 

I'm on PS 1.4.6.2, thx a lot...