Here's the hardware I'm using in case someone wants to pick up something they know will work:
https://www.amazon.com/gp/product/B009U7WZCA
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For rtl_433, any of these NooElec, or RTL-SDR blog units should be fine. I'm using two of the NooElec units for rtl_433.
If you haven't bought one yet, and think you'd might use it for other stuff too, I'd recommend one of the units with an SMA connector and a low PPM oscillator or TCXO. They are only a few bucks more.
There is a lot of good info on http://www.rtl-sdr.com/, including reviews and buyers guides. At the moment, if I were buying one, I'd probably get the RTL-SDR Blog v3 unit with the 2 antennas, but they are out of stock on Amazon at the moment.