I've been thinking about buying intraday historical data for stocks for backtesting strategies. However, high quality tick data is expensive, and what I'd like to do is first pay for collected data, but then start building my own database by automatically downloading data from a website (or a broker, if possible). Does this make sense, or are updates/feeds relatively inexpensive compared to historical data? I'm only interested in high quality data (right now looking at Algoseek.com). It doesn't have to be tick data, 1-minute or 5-minute bars would be sufficient. Also, just need trade and volume data, so no quotes needed. Second, I'm going to need to download real-time price data anyway for live trading decisions. It would kind of make sense to combine this effort with forming my own database for backtesting, no? What website would be the best to collect real-time price data for live decisions? Is it available directly from a broker such as IB at an affordable price? Or should I try exchange websites (such as Nasdaq) directly? What is the industry standard practice (for retail quant traders)?