[mnahkies]

Ibkr gives me close to real time data for about $6 a month - I've not read the fine print closely but I'd be shocked if it is 15min stale. It's localized to certain exchanges but covers most bases. Ultimately any retail investor is unlikely to be able to capitalise on millisecond data without developing their own hft bots

[spitfire]

Last time I was heavily playing with IB's API they were 250ms rollups of the market. So not useful for HFT or anything, but plenty fast enough for prosumer trading.

[mgraczyk]

Even without a plan you can get snapshots for about $0.01 each that I believe are less than 15s old