ready to buy mini - but don't want obsolete product

Here is a problem I see more and more with Apple. I am a longtime user (since 1984). It used to be you'd buy a machine and know it would be a stable product for three or four years. No big changes. Twice in the last two years I have made major investments in desktop and laptop machines only to have new models come out a few months later. Not good. Of course the employees don't know when these releases are coming, or can't tell you, or both. Now I want a mini ipad but I don't want to have it obsolete in two or three months when it comes out with retina display for about the same price. Apple has shortened its product launch windows, no solution for this from my end or any user end. I just wish Apple didn't get so flaky about constant new releases. There should be some sort of discount or guarantee if a new version comes out, say, within three months.