I got the idea for this question from:
The tweet included images of two parallel passages:
Are not two sparrows sold for a penny? And not one of them will fall to the ground apart from your Father.—Matthew 10:29 (ESV)
Are not five sparrows sold for two pennies? And not one of them is forgotten before God.—Luke 12:6 (ESV)
So while the basic message is the same, they include slightly different prices per sparrow. (Matthew reports half a penny and Luke reports 2/5 a penny, which is slightly cheaper.) Presumably a buyer could find sparrow vendors who would offer a variety of prices, so the minor fluctuation in price isn't really a huge concern. More interesting is how they each quoted Jesus' words differently. If you accept Markan priority, this passage is probably from the presumed Q source.
Did Luke do market research to determine a more accurate sparrow price? Or is Matthew doing his thing were he prefers to talk about two things rather than 5 in this case?