I have found that if you buy a lot of premium teas like I do, and when you get low on the quantity of any certain kind of tea (I'm using black teas here from my example), get yourself a spar tin and start mixing the teas that are leftover into the spare tin and label that tin "Black Mixed Tea" and in no time you'll have a unique blend all of your own. And as you keep using the tea from the "mixed tea" tin and adding more back into the tin with the other low teas you'll find that your unique blend will keep on having subtle changes in the flavor.
The same works with green tea and white tea. Just don't mix black tea with green tea or white tea with the other two. Keep the teas in the same family.
But remember that all teas have a shelf life (except for Pu-Erh teas which actually improve with age), so don't over do it with a whole lot of teas. A good rule of thumb is to only buy the amount of tea you can drink in six months or so.