Here is a great overview of a desktop pick-n-place unit from DangerousPrototypes.com:
Today we take a look at an inexpensive pick ‘n’ place machine found on the Chinese auction site Taobao for 22800RMB (about $3,600). A pick and place is a machine that puts electronic components onto a circuit board that has been coated with solder paste. To complete the prototype you just place the populated PCB into a reflow oven. We hope it will speed up production of one-offs and single prototypes.
The NeoDen TM220A is a table top pick and place designed and manufactured in China. Most PnPs are huge machines that take up a room, but this fits nicely in the workshop. It doesn’t require a separate compressor, it has a noisy internal vacuum pump that provides suction for lifting parts.
Up to 15 reels of components can be loaded. 12 x 8mm, 2 x 12mm, and 1 x 16mm. A tray at the front holds larger components like chips. The bigger TM240A that has twice as many reels and costs $1000 more. For us the TM220A is the ideal size. More importantly, it’s light enough to carry up two flights of steep stairs into the workshop.