Got it at Hai chong at paya ubi. U can get every thing there.
It better for u to get a y-check valve also to prevent back flow.
The size of the pipe i use is 20mm.
For cabinet unless u have the skill if not don't DIY.
For a 3' tank with sump & cabinet will be around $750.
Some 2nd hand tank can be very good buy, look around n be patient.
Cheers.