Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) said: Copies of the Qur'an used not to be sold. A man would bring a sheet in the time of the Prophet (peace and blessings be upon him); then a man would stand up and, seeking reward from Allah, write on it; then another would stand up and write, until the copy of the Qur'an was completed.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 11065