It looks like you might run into the same problem with Capercaillie tartan - having to order it special woven.

I ran across this website though: http://www.scottishgypsies.co.uk/

I got to thinking that if you wanted to honor this strand of your family, it might be easier (and less expensive) to perhaps choose a district tartan from Scotland where Gypsies lived. The district tartans often utilize colors reflecting the land, rather than a family, thereby allowing you to focus on the colors of the areas these people lived in. Maybe this would be an acceptable way of honoring them. Also, many of these Gypsies (or Egyptians as they were often called in Scotland) were forcibly removed to the Carolinas in the US. The Carolina tartan might also be a "melting pot" selection that would work for you.