There are loads of decent go-pro lookalikes. Mine is made by Denver and cost £59. Many come with attachments such as watertight cases and stickers for helmets.
There are loads of drones with HD cameras attached. Probably cheaper to buy a drone combination.

You need to start by buying the camera of your choice and then build up the kit as you require add-ons. More important, question why you want an action cam and what will you do with it when you get it before investing in a lot of kit you may never use.