Give the collection a criterion, not just a sequence of purchases

A collection becomes more coherent when it has a criterion: a series, period, manufacturer, technology, circuit type or personal theme.

This does not mean every purchase must be rare or expensive. It means knowing why an item belongs in the collection and what information you want to preserve.

Also define what you do not want to collect: duplicates, heavily compromised examples, undocumented items or categories requiring maintenance you cannot support.

A clear criterion reduces impulsive buying and improves research quality.