Final answer:
The exact symbolic purchase made by Joe is not specified in the provided information but is likely an item representing community and unity.
Step-by-step explanation:
The main, symbolic purchase that Joe buys for the town and then installs toward the end of chapter 5 is not explicitly mentioned in the context provided. However, drawing from common themes in literature, a character named Joe in a story set in a symbolic landscape like Main Street USA might purchase something emblematic of community spirit. This could be a public park, a town hall, or a significant communal amenity like a fountain or monument.
These items are often used in literature to represent common themes such as community, unity, and prosperity. Without more specific information from the text, it is not possible to provide the exact item Joe purchases.