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

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.....

Up to $100. I understand the iFi wallwart is switching, not linear.

An ebayed 5V/2A Chinese Zerozone LPS is a bit more @$130 including shipping.  I've had great results with this powering a JCAT Net Card Femto in my music server.

You could also try a supply house like Mouser, which carries a lot of different products. Type in Mouser and linear power supply. You'll be taken to a page where you put in certain parameters, like output voltage. There seem to be an array of products. Obviously, you want one they have in stock. I've bought parts through them- fast shipping and not overpriced. There are also high quality lab grade ones, used, but that's probably overkill. 
Depending on application, some of these supplies are, at least according to audiophile designers, not robust enough to power a computer run as a server. The audiophile versions can be expensive. If it is not a critical application, one shortcut is to look for a bench supply with a large toroidal- I found one, a little more money than your budget, with three channels of output, two with variable voltage and current. I can post an article about it- got it through Amazon, and though it looks virtually identical to another brand, it was better build. I use it to power a small DSP and a couple other non-critical units to eliminate the switching supplies. 

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! 

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...

Asking for a 5 volt power supply without specifying the current requirement is like shopping for an pair of jeans 👖 only for the length and not the waist. Best bet is building  your own, you can get the best results that way. By the way, what’s the application?

Sleepwalker, good point. For Raspberry Pi based Dac with USB, so 2 Amp is plenty.

Uberwaltz, the Jay's Audio LPS fits the bill. I ordered it.

Thank you.

Ciunas audio good price good product for the money 

I think Wyred4Sound was selling a modular unit.

Small Green Computer has an excellent one that I used in the Audio Blast article of the SONORE systemOptique article at Dagogo.com