My wife (now deceased) had three folk harps. In most of the harp circles she participated in harps with 36 strings were the most popular. 36 string harps can still be carried by hand and are big enough to produce a decent amount of sound. Most harpists want a full set of levers in order to play in as many keys as they can. The folk harp is a diatonic instrument except for triple strung and cross strung versions. There are many fine luthiers making folk harps in many regions of the USA and Canada. My guess is you can find makers of quality harps near your store with whom you can do business. Dennis Doyle, an accomplished folk harpist in Calafornia, used to keep a record of good harp makers in various regions. He may be able to point you to good luthiers. Google Dennis Doyle and his website will be the first hit.