Multiple Price Lists

[tredi]

I need to setup a Prestashop website for a customer who has different price lists (not different percentages, actual different prices) for every customer group.

Is multiple shops the only way to do it or are there modules or other ways? 

The only problem I have with multiple shops is that I think I wouldn't be able to track the stock, as it's the same stock for more than one shop.

Thanks for any suggestion!