You can use the screws and rods you can find easily, of course some dimensions will change and is needed to adjust parameters.
I used in my first 3D printer and standard screw of 9.5mm (3/8) the main problem was the coupling available in Mexico that werer none on that time.
You can buy the bearings on Ali Express, they can send from there to Mexico, I guess they can deliver on your country.
The bearings has these sizes:
where is Number ID, inner diameter, outter diameter, width.
Don't try to use 6000 :D is a little complicated to reduce the size for a proper coupling if you don't have a lathe. My 3rd Printer will use this kind of thread because is easily to find with no warpage and now I will use a lathe to reduce the coupling area to 8mm or 5mm since I have on hand the couplers.