Is there a place where I can find apples which have not grown near crab
apple trees, for planting seedlings?

For what purpose? Commercial apple orchards normally do not contain crabapple
trees, which are primarily grown as ornamentals in home gardens.
There is no point in amateurs growing apples from seed, except to amuse the
children. Open pollinated seedling fruit trees probably will not produce fruit
for 10 years or more, and then the fruit is likely to be inferior to named
cultivars. The only reason for growing apple trees from seed is with controlled
pollination for hybridizers to produce superior varieties.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)