To get good quality slow motion, you need to record with a slow motion camera. Adding the effect afterwards with software tricks looks terrible.
You can do reasonably cheap (around $300) slow motion video with cameras such as the Casio Exilim EX-FH100
, but only at quite low resolution (120fps at 640x480), and for short periods (a few seconds at higher frame rates). If you want something better, you move quickly into the multi-thousand dollar bracket.
The linked clip was shot with a Phantom HD Gold, which costs around $115,000.