A fine example is DDR memory.
I was going to add another gig to my system of DDR PC3200, but as I learned from some of the guys here at the 'Mech - alot of companies are slowly phasing out of the production of DDR and raising the production of DDR2, which is being used more and more.
So 6 months ago, when I was going to add more memory, I though "hey! I'll just wait a couple months, and prices will start dropping"
Well when I went to crucial.com to order some more DDR, i found that the price had risen about $20, which to a 16 year old working and paying for gas (me), is also of money.
Morale: Technology is unperdictable