I'll be staying in Palermo Hollywood. Where is the best place to buy River Plate memorabilia? Also, do taxi services from Ezeiza Airport accept payment in US dollars in cash?
The best suggestion is to visit the stadium for a tour on a weekday. At the end of the tour, there's a shop where you can purchase memorabilia. I did the tour in November 2022 when the stadium was still under construction, so your experience should be much better.
By the way, the walk up to the stadium from Belgrano is really pleasant. You pass by many lovely family homes, which might be of interest to you as it was to me.