Choosing a vacuum pump for fractional distillation
If you are keeping your hands on you can't beat a water aspirator for cost, simplicity, and chemical compatibility.

Here is an aspirator assembly with a gauge and valves I put together for about $50.  Connecting it to a standard hose bib it can pull up to 27mmHg.  The water valve controls the vacuum rate, and if you have a closed system once you reach the desired vacuum you can shut one of the other valves to hold it.



Note: This was inspired by Lysander's answer to my similar question last year, which has additional useful details.