Test signal for gnu radio

Gladly I will start by using GNU radio but before I went to the shop and
build me expensive hardware I would like to train myself somewhat
therefore I’m looking for a dump from an analog digitizer in a frequency
range of let say 10Mhz to 100Mhz.

So that I can use this test signal to become familiar with gnu radio.
Where can I find something like this? Who can help me?