Just wondering if anyone knows why the price on canon 17-55 F 2.8 lenses keeps rising??

I may be buying one soon,last year I bought 2 canon L lenses,a 400 prime and 70-200 f2.8 both of these have droped hundreds of dollars,( I paid $1637 for 70-200 now$1550) and a bigger drop for 400 prime.

I looked at buying a 17-55 F2.8 to fill in the focal range gap a few times and it has risen $100 since I have looked,added the price of the hood,and it will be dearer than the 70-200 F 2.8,and its a L lenses,why is a plastic EF-S lens dearer???

might look at a Tamron 17-50 VC half the price,

regards FB