I have developed an allergy to soy which includes soy flour aka soya
flour. I love potato rolls, a popular bread product local to
Berks/Lancaster Counties PA where I live. The more popular potato roll
brands, like Martin's, Stroehmann, and Maier's, contain soy flour.
Other brands, notably Holsum, Blue Bunny, and Schmidt, are
comparatively lame in taste, color, and texture. How can I get my
hands on delicious yellow soya-free potato rolls short of making them
myself?

Pototo rolls are absurdly easy to make at home. Why not try your hand
at preparing your own? I would wager that the Google Answers
researchers could give you some very tasty recipes.

I'm afraid you may be stuck with the lameo rolls.
It is the soy flour that gives Martin's, Stroehmann, Maier's and
others that lovely yellow color, great taste and texture. Soy flour is
yellow and it is made from roasted soybeans that have been ground into
a fine powder giving it (in my humble opinion) a much better flavor
than white flour.
You can see a picture of soy flour in the Cooks Thesaurus at
http://www.foodsubs.com/Flournw.html
(scroll down to the end of the page Soy flour is the 5th from the
bottom)

In case you'd like to try making your own, here is an excellent
recipe:

OKLAHOMA TATER ROLLS

1 cup mashed potatoes 
1 cup very warm water 
1/2 cup sugar 
2 packages active dry yeast 
4 to 4.5 cups all-purpose flour 
3 eggs 
1 stick butter, melted 
1 teaspoon salt 

Put the mashed potatoes, water, sugar, and yeast in a large bowl. Mix
well. Add 1 cup of the flour, and mix until smooth. Add another 1/2
cup flour, and mix. Cover loosely, set in a warm spot, and let rise
until doubled in bulk (usually about 1 hour.)

Add the eggs, one at a time, mixing after each addition. Add butter
and salt, and mix well. Slowly add 2.5 cups flour, mixing vigorously.
When the dough becomes too stiff to mix in the bowl, turn it out onto
a lightly floured surface, and knead it until smooth, about 5 to 10
minutes. Add a bit of flour (no more than an additional cup) as you
knead to keep the dough from sticking. (It will still be softer than
typical bread dough.)
 
Lightly grease two 7 x 11 x 1.5 inch baking pans. Re-flour the work
surface, and roll the dough out until it is about 3/4 inch thick. Cut
the dough into 2-inch squares and place them into the pans, leaving
about inch of space between them. Cover the pans loosely with a damp
kitchen towel, and let the rolls rise until they have nearly doubled
in bulk (about 1 to 2 hours.)
 
Preheat the oven to 350 degrees Fahrenheit. Bake the rolls until they
are golden and puffed, about 12 to 15 minutes. Turn them out of the
pans onto a wire cooling rack, let them cool for 5 minutes, and serve.