While I can not suggest a source of plants in Malaysia, if you find they are not available it is generally propagated from seed and grows very rapidly if it is provided with an ideal habitat. There are numerous sources of seed online and many would be willing to ship them to Malaysia if you can not find plants
The authors from this lab (in Malaysia) are using tissue culture (from seeds) for mass production of Artemisia annua L. plantlets for their research (see attached paper). You can contact with them to find out the materials.
BioMed Research International
Volume 2014 (2014),
http://dx.doi.org/10.1155/2014/215872
Research Article
Antimicrobial Activity of Artemisinin and Precursor Derived from In Vitro Plantlets of Artemisia annua L.