A new 868 MHz module came in today, which uses FSK as modulation method:
This is a tiny 16×16 mm RFM12B module. It contains a transceiver and can be connected with a 4-pin SPI bus plus an IRQ pin to send/receive bytes using interrupts. Documentation is a bit sketchy, but there are a few different code samples on the net.
This version is for SMD mounting (with 2mm pins, again). But it’s easy to add a few wires and use this in a 0.1” grid breadboard. The antenna used here is an 82 mm straight wire.