The product in spotters has little bearing on the price it is actually the time producing them which makes up the bulk of the cost. We actually put the labels on as well not just supply them in sheets.
When giving free chemicals away you also have to consider what liability you are opening yourself up too. By giving away a Microsplitter, which works, there is very little risk imparted by you because if a child was to get their hands on it and drink it it would do them no harm.
If you were to leave them a harsher chemical containing solvents lets say, then the the consequences could be a lot worse. You would also have to be covered under your liability insurance to supply chemicals which isn't standard and needs to be added to your policy.
Then we had the clown a few years back who left their customer some Champion in a Coke bottle. Her 4 year old son drank it and was seriously ill.