Taxes would of course need to be paid for any item exceeding RM500 which at our current exchange rate covers just about everything. It all depends how diligent the Customs officers are at questioning you or your conscience.
As to prices, I used to be told that some things are actually more expensive in Japan and the only items worth getting are JDM or Japan Domestic Market, meaning they were never intended for sales or marketed outside of Japan, officially that is.