I got by with a Black and Decker $30 burr grinder from Target. Broke down twice in 18 months and got replaced under warranty.
Recently upgraded to an Ascaso i-Mini which was $285 from http://www.seattlecoffeegear.com/ and the difference for espresso is very noticeable. Still keep the Black and Decker for coarse grind though.
If you're just grinding for drip coffee/french press then a cheap burr grinder is fine. For espresso, it's worth saving up for a decent grinder.