Cheap 50s are great. Here's an even cheaper 50mm lens, a Zuiko 50/1.8 I got attached to an Olympus OM10 for about NZ$40. Used here on an Olympus e-520 as a 100mm equivalent portrait lens.
Jack by Mark Bowerman, on Flickr
Same lens native on an OM2n, Ilford HP5
Wellington by Mark Bowerman, on Flickr
The nearest I get to 50mm equivalent in m4/3, a 20/1.7 Panasonic on a Lumix G3. That PanaLeica 25/1.4 is sooo tempting but sooo expensive.
Broadstairs by Mark Bowerman, on Flickr