How do I append a dictionary with random prices from original starting point

Imagine I start with 5 stocks

dict1 = {'BA':57.0, 'QQQ':545.5, 'AAPL':150, 'SPX':245.5, 'JPM':150, }

how can I increase the dictionary to hold say 500 random prices for each asset from the original starting point?

so I get; BA: 57.0, 58.2, 59.6, 59.9 .........

Many thanks