$40 is an average price for a 430EZ. It is not a "deal".
I used my old film era Canon 430EZ on my first DSLR (EOS 10D) until I got a 430EX.
As John said, it will fit but, it is not designed to operate on DSLR cameras. The 430EZ is designed for A-TTL and is not compatible with E-TTL flash metering. If used in auto-flash, it will always fire at full power because it can't read the ETTL flash metering.
BUT, It does have a manual mode and can be used to fire at lower power settings. Maual setting available are 1/32 1/16 1/8 1/4 1/2 and 1/1.
It still has some auto features that work WILL with the new Canon DSLR's.
1) It will auto zoom the flash head to match your lens focal length.
2) It will show your flash coupling distance for the power, ISO, and aperture you set,
3) Will display aperture selected on your camera
4) Will display ISO selected on your camera
5) Will display "Flash Ready" icon in viewfinder
Canon Knowledge Base: 430EZ Speedlite : How to set the Speedlite for Manual Flash mode
