Is there any good trick to target small lists in Facebook? Small lists which are pixel tagged about 500 or so audience. Small lists are quite expensive to target and they ain't getting cheaper as the time is passing.
If you have to cut budget as because they are expensive then I will strongly suggest that you make the campaigns as much as effective as possible.
Target small but go for the highest bids, the ones that you know if do it alright cannot fail. Pick a frequency of targeting and then vary it slowly.
The thing is with small list you cannot do much experiments. So, gather as much as actionable data you can first and then act on it.
This is the reason why we choose fb just to do outreach. If you trying to target leads then it will get expensive.