iPhone SE finally released at the end of March 2016 and everybody will get surprise why the new family member is such bargaining, although it equips similar iPhone 6S features. According to the teardown from Chipworks, we may get the answer. From the teardown, we discover some known iPhone 5s and iPhone 6 chipsets. 
According to the teardown pictures from Chipworks, we can find that both iPhone SE and iPhone 6S adopt A9 processor with serial number APL1022 and date code 1604 hinted that it is come out from January. About the DRAM, both phone models use SK Hynix 2GB LPDDR4 RAM but the date code 1535 hinted that they come out from last year August and September 2015. iPhone SE adopts older 19nm memory, although both are Toshiba 16GB and we suspect this is one of the clearance components.
Regarding to the iPhone SE LCD Screen Assembly, the digitiser control component we observed from the teardown is Broadcom BCM5976 and Texas Instrument 343S0645, which is same as iPhone 5S. SE adopts Qualcomm MDM9625M and WTR1625L Modem and RF receiver. Components which are same as iPhone 6S are 338S00105 and SS8S1285 (Sound control), NXP 66V10 (NFC). The only new component is 338S00170 which is a power management IC.

As a result, we can deduce that the come out of iPhone SE is to clear the overstocks of partial old components and that is why the price is such bargaining. 
Photos from: Chipworks