Strange as it seems, mice make wonderful pets, although they are not as 'kissy' as rats, or as loyal or affectionate as cats or dogs. They do tend however to make their owner sit for hours infront of their cage watching their every move (personal experience).
They are generally a cheaper alternative to owning a rat, although if you are buying a very fancy breed from a breeder, they can start to become expensive. I am not going to kid you into thinking taht you only have to buy a $2 mouse and you are a mouse owner, there are other things to consider, but these will be discussed in other parts of this web site.