What Was the Name of that Book?

Can anyone help me remember the name of a book?

It was about a girl. A new Russian neighbour moved in across the street (I think, possibly next door). I think it was set in the late 80s/early 90s (possibly written around that time, too) because it talked about the fall of the Soviet Union. It used words like glasnost. The neighbour gave the girl a gold pin (possibly from the Moscow Olympics?) and the main character would check the stock market to find out the price of gold. All of this happened fairly early on. I don't remember the rest of the book at all, but the main character probably learned a lesson or two about life. I think it was a paperback and I probably got it from a book order or something like that.

Does anyone remember this but me?