If it is only the essential three, for me they are;
Circular Polarizer
Tripod
Remote Control/Intervalometer
The first two I wouldn't scrimp too much on, but savings can be made on a Remote Control/Intervalometer.
There are other things that are useful and makes things easier, like a comfortable camera strap. I have had a TP one from many years ago, which I think was an Op Tech strap with TP branding on.
Extra batteries and memory cards.
ND filters.
An individual case for camera and walk around lens, for when I am generally toodling around a location with nothing in mind, travelling light.
A backpack to put it all in. I use a general purpose backpack, as I use it for other things too. And it is less conspicuous when out and about with £'s worth of camera gear.