Source for 28 years of intraday bars?

Summary

• The post is a request for free or low-cost sources of 28 years of intraday bar data, covering the dot-com bubble and 2008 financial crisis.
• The author has already backtested from 2010 using DTN data and is seeking extended historical data to improve robustness.
• Quality assessment: This is a practical, well-researched data-sourcing inquiry, not a speculative thesis. It is noise from a trading idea perspective.