Hey samy
The PRS-T2 went down to 99 Euros last year during christmas at the major bookstores in Germany and I expect the same with the T3. The PRS-T2 got it's last update in december 2012, maybe the same will happen with the T3.
The T3 does have an option to integrate the webshop of the bookstore at the Reader's home screen, so some small stores might want to sell the T3 cheap to promote their own Ebook store.
Or short version: If you wait a bit, you'll get your Sony Reader a bit cheaper and better for sure and there won't be any need to update the firmware of your Reader three or five times.
If you're a big Sony fan and you want to own each of the three colours of the T3, you could buy one Reader now for 140 Euros and the other two in december. Even if they cost 120 Euros then, you'd still save some cash.
The price of the cover with light didn't drop in the past. And keep in mind that you need a Micro SD card for each Reader, this is an additional plus of 20-30 Euros.