Where to get a modestly priced 5 volt Linear Power Supply?

Lots and lots of 5v lps on the Bay

This one from Jays Audio is likely not the worst of the bunch for sure and price is fair,



https://www.ebay.com/itm/DC5V-USB-15W-2-0A-Linear-Power-Supply-Dual-Output-CAS-XMOS-Raspberry-DC-reg...

The iFi unit is not lps correct but also is vastly different to your common garden switching ps walwart.
As I said depends on your budget, just my results I was sharing.
Good luck in your search! 

EBay as good as anywhere.
Or try an iFi power supply at $50 on eBay, they do them in various voltages including 5vdc and come with a selection of tips to fit most units.

I upgraded a Mytek Brooklyn from mains to an iFi power supply and it was very noticeable.

Of course it also depends how much you want to spend.....