heres my bicarb-viniger set up i've been using for years.cheap ,effective and not messy.you need-
-a reasonably good quality plastic bag(not a thin woolies one)
-a shoelace
-a piece of hose(3/8 fuel hose works well)
-1 airtight plastic container
-plastic funnel
-10mm plastic knitting needle
shouldn't cost more then $10.drill 2 holes in the plastic container for the hose and funnel(if you drill then slightly smaller and force the hose and funnel in you shouldn't need sealant).put rats/mice in the bag,put in the other end of the hose, squeeze out most of the air from the bag and tie it off with the shoelace to seal it.add 4-3 tablespoons of bicarb soda to the container and put on lid.add 1 CUP (not 1 litre) of viniger to the funnel with the knitting needle in place to seal it.add the viniger by pulling the needle out slightly then sealing it again.add the viniger in about 3-4 steps over 1-2 minutes.the bag will expand with co2 and the job will be done in a few minutes.
ps.having the rats in a bag works better and quicker then rats in a container .