JAndy -- I avoid squeaking strings by using plain steel bass strings of a slightly smaller gauge than the recommended wound steel.

Somewhat off subject, but in the past couple of years, flatwound or squeakless stings have become availabe for the laarger diameters.  I hifghly recommend them as they are squeakless..

If you want the exact gauges that Warren specifies for his instruments, as others have said go to Juststrings.com and order a 12 pack of each of the gauges:
Plain Steel Bulk Guitar Strings (juststrings.com)

At about $3 a dozen you'll have several years worth of strings for about $10...

updated by @ken-hulme: 01/07/24 03:24:05PM

One basic point in looking for strings. Until about 10 or 15 years ago, there were no "dulcimer strings." Ball end strings were part of the guitar string rack while loop end strings were banjo strings. Either will be more than long enough.

Just avoid violin, mandolin, and ukulele strings or you will end up with something too short.

I hypothesize that many of the early builders bought banjo strings from mail order vendors like Sears. Some would have purchased rolls of piano wire and put their own loops on it, but a roll of piano wire is pretty long and might be a lifetime supply.

GreatLakes 73, the others have given you the advice I would have given. Unless you have a Folkcraft or McSpadden who market specific strings for their instruments, dulcimer players should buy individual strings and make up their own sets. I'm surprised how often in doing repairs and I need to restring someone's dulcimer they are surprised to find that I don't have specific sets but rather have tubes of individual strings in various gauges. Many times they come back to buy strings from me even though I tell them they get the strings from JustStrings.com or from other vendors. Of course, that also means that they want me to change the strings for them. I hope you find what you need.

Ken

"The dulcimer sings a sweet song."

 
Hello great lakes. I am aware that "Folkcraft" sells a set of ball end dulcimer strings. The gauges are not exactly the same, but very close. Seeing if your local guitar shop sells loose strings is a good idea also. Often times then have a big tub of them, like John says, and can grab out the exact gauges you want. 
Nate

Strings.com or Guitar Center.  I go to Guitar Center for odd sizes, or when I run out of the proper string.  They have a box of individual strings under the counter, in square paper envelopes, and can usually find me what I want.

I use Just Strings.com. You can get individual strings there. Warren May will sell you a set I am sure. He is still making a few dulcimers at his shop at home.

Hi everyone, looking to buy some strings for my Warren May dulcimer, takes ball end. In his papers that came with the dulcimer he notes .012, .012, .014 and .022 for the string sizes. Most of the “sets” I’m seeing are different gauges or are loop end. I went to d’addario web site to look at just getting individual strings but the options were a bit overwhelming. Any suggestions?