You can buy a cheap chinese USB soundcard on Ebay for £1.50 with free postage, I've got three. Microphones work, but I havent come across a cheap one that records in stereo, mine are all mono recording, I suppose you could modify your recordings in Audacity to make them mono on both channels.
Pi 2 running LibreElec Krypton, Pi 2 running Wheezy Desktop, Pi 1 headless Wheezy, downloading Radio, Pi 1 running Picore headless Media Server, Pi Zero to be an Old Time Radio Project. Pi 3 testing. Pi Zero W downloading Radio shows headless.