I recently read somewhere where, and please don't laugh, someone actually
used a metal slinky toy as an antenna in just your situation.

What's to laugh at? The Slinky-as-antenna concept has been around for a LONG
time, and has many, many proponents in the SW and amateur realm. Do a search
for 'slinky antenna' on google or your favorite engine, see how many hits you
garner.
I've experimented with Slinky antennas in the past, but more out of curiousity
than outright need (I use a 75" sloper and a large horizontal loop 'skywire',
about 200" a side, for my outdoor antennas) but they can be rewarding antennas.
For about a year I had an indoor Slinky antenna 'loop' running around the
ceiling in my room, all four walls. When storms or wind were howling outside,
or in snowy conditions (blowing snow and sand can cause a LOT of static
build-up on a longer wire antenna!) I could still do some rather nice listening
without fear of frying my radios. Worked pretty well on my scanners, too.
And you're right, it's cheap and it's fun!
Linus