andagol said:

What is the best choice for the cDNA labelling: indirect or direct method?

For direct cDNA labeling system for microarray look into Invitrogen's product called: SuperScript Genicon RLS cat# L1017-01, Invitrogen: 1-800-955-6288.

For indirect labeling of fluorescent cDNA targets for microarray look for Promega's product called ImProm-11 reverse transcriptase. Promega: 1-888-544-8524