AirHint found the following cheapest return flights from San Jose (SJO) to Buenos Aires (AEP) in September 2025 (see full year).

Return flights

27 Sep - 03 Oct	GOL Linhas Aéreas
06 Sep - 19 Sep	GOL Linhas Aéreas
13 Sep - 20 Sep	GOL Linhas Aéreas
13 Sep - 18 Sep	GOL Linhas Aéreas
01 Sep - 19 Sep	LATAM Airlines Group
14 Sep - 18 Sep	LATAM Airlines Group
14 Sep - 20 Sep	LATAM Airlines Group
15 Sep - 21 Sep	LATAM Airlines Group
08 Sep - 29 Sep	Avianca
16 Sep - 23 Sep	Avianca
12 Sep - 25 Sep	Avianca
12 Sep - 19 Oct	Avianca
13 Sep - 19 Oct	Avianca
13 Sep - 17 Oct	Avianca
14 Sep - 19 Oct	Avianca
19 Sep - 20 Oct	Avianca
15 Sep - 19 Oct	Avianca
30 Sep - 05 Oct	Avianca
26 Sep - 04 Oct	Avianca
14 Sep - 15 Oct	Avianca

Also check the deals for one-way flights from San Jose to Buenos Aires in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from San Jose to Buenos Aires in September from 388€

Return flights