try your local music library. i think i saw several records, though i don't know about cd's with music minus one titles. don't know about the net.
if you are going to a regular library - how hard is it to request items like this i wonder? suppose it depends on the librarian and how friendly they are. some like to prove their librarianship by getting all kinds of things for the library.
i can't afford to buy everything retail anymore. i spent a lot of money last year on concerto cd's. now, i see it's really a matter of being more frugal and perhaps even making your own (albeit maybe not perfect sounding - but tempos that you want). for me, i'd have to ask my teacher if he would be willing to do this - as i'm not even sure of th etempos i'd want. i like to get a general feel for things by his taste. guess i'm sort of a sponge. BUT, i do remember good tempos and interpretations when i hear them on the radio. it sort of sticks in my head and i think - ok, that's how to play that!
music minus one - your kind of stuck with whomever is interpreting it- right? but, then you can change it if you put your mind to it. whatever i practice over and over usually stays the same - so i'd need a recording that was EXACTLY how i wanted to play it.