It is a custom, if you go to a temple, to take a small offering such as flowers or food. If you talk to a master for long periods, you may wish to leave a small donation. If you have a strong interest and are sincere but have a financial problem, this can be discussed with the organisers. The teaching is not supposed to be denied to people who lack financial accumulation. New students who have only just discovered Buddhism tend to want to tell all their friends how wonderful it is.
Older students know everyone has their own path and their own pace.
Buddhists are human. There are a few bad organisations. It is obligatory to answer truthfully questions concerning one's teachers and lineage. The teachers one finds in Buddhist temples, especially if they have been trained traditionally, overseas, are incredibly qualified, with decades of experience. If a temple is open and honest, if it is connected to the mainstream of Buddhist tradition, then it is almost certainly okay.