Like all hunting waterfowling can be done high-tech or low-tech both can/will provide decent results.
Yes, in my experience the Mojo style mechanical duck do work very well. For that reason some states have banned them. I have used them very successfully though I kill plenty of ducks without.
For calls if you are not recently practiced you might try a simple/cheap double reed call. These are great for beginners. I did great for the first ten years or so with a cheap double reed duck call and a goose flute. I have since transitioned into higher end single reed and short reed calls but only after becoming proficient at actually calling in birds and not just squawking at them.
I had lots of 200+ duck seasons with a bag of ecomomy flambeau decoys and a $20 Big River call with a pump Mossberg.
Now I have Mojos, SBEII, lots of high end dekes, and expensive calls and I don't kill many more birds. It's just more money to spend and gear to carry into the field.
FWIW I would start with a lower end beginner call and re-learn how to use it well. A $200 top of the line call is useless if you can't make it sing like it's supposed too. GHG decoys are good for the money these days. Buy a Mojo if it suites you but they are not required to kill birds.
Take the time to pattern you shotgun. This will be the single best investment you can make as a waterfowler. There are lots of brands and price points on the market. Find out what your gun likes and that will result in FAR more birds in the bag than expensive calls and motion decoys.
