howto display price for small quantity and ask for price for bigger quantity

[NUA76]

Dear all ,

Somebody know how to implement following sketch

In virtuemart  when cost price is set to 0  ,  on front end  there is a button " ask for price " and when customer click on it , it will open popup for asking price
but i want to set it  another way

from  1 to  5  products  display price and give possibility to add product to cart and if customer add upper 5 products , i want to display ask for price button and hide add to cart

But if  in product price , you set cost price to 0 , you can not add a new price .  On the other side you set cost price to 1 $ for product range 1 to 5  and add a new price = 0
for quantity upper 5  when you save the product  , this second price is not registered

I have found a solution using multi variant but this is really not simple and not workable if you have a large volume of product

help will be welcome

[Milbo]

I think the right way is a js, checking if you go up quantity x, which then create the button "ask for price".

for quantity upper 5  when you save the product  , this second price is not registered

Or just do a core hack or better said, find the reason why it is not stored. When you post it, I may consider it as bug anyway and it is not even an hack then. Just a bugfix.