All depends how pretty you want the power supply to look. The pretty ones can cost a lot.
I use industrial linear regulated power supplies from Acopian, they are built to last forever so I always buy used on eBay.
Acopian 5EB200 5v 2 amp linear power supply. ($20 on eBay)
Load 0.25%, Line 0.05%, Ripple 1 mV RMS
Acopian B5G400 5v 4 amp linear regulated power supply ($45 on eBay)
Load 0.3 %, Line 0.1%, Ripple 1.5 mV RMS
I use the Acopian Series B - General Purpose (model numbers begin with the letter B) Gold Box power supplies, they are always available on eBay.
If you want the very best can go for the Acopian Series A - High Performance (model numbers begin with the letter A). The regulation and ripple specifications beat any PSU available.
Load + - 0.005%
Line + - 0.005%
Ripple 0.25 mV RMS
I go to the Acopian website and look up the model number of the power supplies that will work and then paste that number into an eBay search. They never hum or buzz and run cool. I never had one fail.