Where to buy a cheap bike saddle

I'm wondering where I might buy a cheap (used or new) saddle for a standard city/touring type bike. It's a borrowed bike that I've been riding around on for a week and I didn't even notice until after the saddle was stolen that it had a quick release.

Really don't want to spend too much; would even consider buying a cheap-o bike just for the seat if it's going to be over 20€.

It was stolen between 22:00 and 24:00 in front of the KVR at Poccistraße, for those who are curious. Seems someone went down the line of locked-up bikes taking everything that wasn't bolted down (there was another saddle on the ground next to my bike [different seatpost diameter] and the neighboring bike's handlebars were snatched as well).

Any sports store, bike shop, or somewhere like Real, Kaufland or OBI.