Different stores for different products and it depends where you live.
Buriram has a good independent building supplies/hardware store.
Where I live we only have one big chain store. But they don't stock AC plastic trunking .
Most domestic pumps put out about the same pressure they operate at 3 bar with a max of 4.
Blue plastic pipe is rated for about 10-13 bar. If it hasn't been in the sun for 5 years the plastic pipe is probably as good as new.
I would not worry about installing a pump.
Just because all the vans are parked at an overloaded hospital in Northampton, doesn't mean they won't attend if one is having a heart attack or had a road traffic collision.