Comment to how much cost me finally a complete Una ?
Each PowerApp is priced individually. You have option to rent it by month or year ($ 50 / month or year). If the price is not mentioned as per month or year, then it means you buy it permanently (mostly third party Apps are available in this category).
You cannot buy all Apps in one go, I think those are available under Big price plans, which you can browse in Marketplace and will understand it based on above guideline.