You got into the wrong type of hunting to be worried about expensive...
Half joking there but it is not cheap. You can buy once, cry once and go with something by Drake or Sitka or you can find other cheaper options.
The good news about duck hunting, especially if you already deer hunt and have camo, is that you really only need to worry about waders and a jacket. I had a cheap game winner waterproof jacket in Max-5 that worked perfectly for the first two seasons. Layer up underneath and you're all set.
I now have mostly Sitka stuff but 95% was purchased either through guide discount or on sale. It's really good stuff but it's not "needed".
Check these website for sales and gear:
https://www.rogerssportinggoods.com/https://www.mackspw.com/Sign up for their email alerts if you really want to go broke