When I have more money, I would use 100 Proof (50% grain alcohol) Vodka which is Smirnoff blue label. But I would usually buy any cheap 80 proof Vodka from local grocery stores and it works fine as long as the herb is not hard material like tree bark which requires higher percentage of alcohol. So far I've made Brain, Cayenne, Lobelia, Liver, Echinacea Plus, Super Tonic and Valerian Root using cheap Vodka and I'm satisfied with the quality. BTW, I would usually let it sit for at least 3 months.
Pressing:
I actually use a juice press for this purpose as well. Mine is a $59 industrial press with a juice tray and juice bags I ordered from Norwalk.
$59 shop press:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=1666
My set-up:
Just recently I made Liver tincture (milk thistle/oregon grape root/dandelion leaves) and used this press. It worked great just like regular juice.
I believe this is one of the cheapest ways to have your own juice/herb pressing system at home. (It takes up some space though.)
Kentaro