can one use a toaster oven to bake cakes and cupcakes?
I don't know what a "mini oven" is, so I will skip this one. 

You should not, under any circumstances, get a microwave. A microwave is not suitable for baking. There are models which are supposed to be a microwave and convection oven at once, but I have frequently heard of them not turning off the microwaves when in convection mode, despite the manual saying otherwise. If you happen to get such a model, you will not be able to bake cakes in it. 

I have a toaster oven of this type:



It serves me well for all kinds of cake and bread baking. Whatever has gone wrong with my cakes, I never had the feeling that it was the oven which was the obstacle to them getting better. 

As far as I am aware, you cannot use the tiny toaster ovens which are only about 15 cm deep. I have never tried it, but I would be afraid that the heating elements are too close, and also you cannot fit a cake pan in there.