Penzey's sells dried/crushed aleppo peppers, apparently. You can get either aleppo peppers or pepper paste through Amazon, but not aleppo pepper paste.
Not sure if I've helped...
ETA:
This Epicurious recipe says:
Quote:
If using Aleppo pepper, place in large bowl and mix in 1 tablespoon warm water. Let stand until thick paste forms, about 5 minutes.