加购

1. • to buy (sth extra) to make an additional purchase

Character by character

• 加(jiā)(used before a disyllabic verb, often after an adverb like 不 bù, 大 dà, 稍 shāo etc, to indicate that the action applies to sth previously mentioned, as in 稍加改良 shāojiāgǎiliáng "make some minor improvements to (it)")
• 购(gòu)buy