buy the concentrate and equal amounts of distilled water and mix it yourself, its not rocket science.
1 litre concentrate + 1 litre water yields 2 litres 50% mixture coolant.
Its also great when refilling a completely empty system after flushing. But for your car if its been using coolant all its life, just buy some Honda type2 (blue - sold as premix only) and do a standard drain and fill.