Matt, if you checked it when you got home, and the
oil was dirty, and you say the
oil filter had "all kinds of trash" in it, then go and speak to the dealer principal. If you go straight to the Toyota distributor, they will ask if you've spoken to the dealer about it, so you should do that.
Do you have a local motoring organization? You know, the sort that provides roadside assistance and other services? They would probably have a legal office that can advise in situations like yours. Also do you have a government consumer affairs office? Talk to them.
I had a problem with a car dealer and spoke to the two offices I referred to above, and I asked if they had many complaints about this specific dealer, and they both said "can't say about specific dealers, but can say that there are NO delaers that we haven't had problems with".
Chances are, unfortunately yes they are trying to screw you, and most of their other customers as well.
Cheers,
Glen