売買の買とbuyの関係はあります？

Question

買 in 売買{ばいばい} is pronounced ばい. The word "to buy", which is the translation of 買う, sounds the same. Is there some sort of connection?! 親父ギャグだけなのか…？

Answer 1

From Online Etymology Dictionary

buy (v.)

Old English bycgan (past tense bohte) "to buy, pay for, acquire; redeem, ransom; procure; get done," from Proto-Germanic *bugjan (source also of Old Saxon buggjan, Old Norse byggja, Gothic bugjan), which is of unknown origin and not found outside Germanic.

The surviving spelling is southwest England dialect; the word was generally pronounced in Old English and Middle English with a -dg- sound as "budge," or "bidge." Meaning "believe, accept as true" first recorded 1926. Related: Bought; buying. To buy time "prevent further deterioration but make no improvement" is attested from 1946.

From 新漢和大辞典

【買】

[常用音訓] バイ・かう
[音] バイ（漢）・メ（呉）
mĕg – măi (mbăi) – mai – mai (mǎi)

Only looking at the development of these two words in themselves, it seems to be very unlikely that there is any connection between 買【ばい】 and "to buy".

Answer 2

ないです。

It's only a superficial coincidence in present-day pronunciation.

The word corresponds to English buy is assumed to have been pronounced like *bugjaną //buɣ.jɑ.nɑ̃// in Proto-Germanic period around 500 BC. Meanwhile, 買 is assumed to have been pronounced like *mˁrajʔ (Baxter-Sagart) or *mreːʔ (Zhengzhang) in the Central Plain of China. It still retains m- consonant in most Sinitic languages (dialects).

The reason why we have b- for this kanji is that, Buddhist monks imported Middle Chinese vocabulary through Chang'an (the capital of Tang) dialect, which showed denasalization making m- into mb-; they transcribed it with then-prenasalized consonant ⁿb-, which corresponds to today's voiced b-.