Each fruit/vegetable shop, whether owned by a Bolivian/Peruvian or an Argentine, negotiates wholesale prices based on longevity of doing business at the Mercado Central, etc.
I have been shopping at the same verduleria in my neighborhood since 2005. Quality of goods plus prices have always been highly competitive.
It's a family owned business....mother/father (both born in Bolivia), 2 daughters, a son and a myriad of cousins all born in CABA. The couple opened their first shop 40 years ago in Caballito. To date they have invested in real estate in our neighborhood....2 verdulerias plus a 6-unit apt building adjacent to the main verduleria (where family members + their employees are housed) plus a Mercedes Benz truck. The 19-yr old son is studying accounting at UBA as well as working part-time 7 days per week in the evening at both their shops.
Every year from Jan 15-Feb 15 they close both shops. Everyone goes to Bolivia on vacation.
While they are closed I shop at another store in my neighborhood. This one is owned by a family of Italian origin. Three generations under one roof which includes ownership of the store plus (4) apt units above the store.