For a quick reference...
Tesla Motors - 0-60 in 3.6 seconds, 135 mpg equivalent, 250+ mile range.
Price - roughly $90k (they have allot of sweet stuff in it)
Miles Automotive - To be released in 2008, 150+ mile range, specs n/a
Price - $30k
Your own conversion - (not including any tools) anywhere from $5k to $30k depending on what you do. Also keep in mind you can sell the parts you remove from the car. Plus this can be an awesome project to show off to all your friends.
Have someone else do the conversion - Ummm look it up yourself because it's not available in most areas but people do offer it.
EDIT - check out the link in my next post it has a few listed....