Guys,
Thanks a lot for feedback.
My budget is flexible, but i don't want to go higher than 300$ for sub. But it doesn't mean that i must get one for 299.99

Lambda for 160$ sonds right.
I don't want it to play loud - i want to have Home Thieter effect - "You can't notice the subwoofer on, you only can notice when it's off"
2Gsport: Do you need your rear seats down to listen to the subs?
The Honkeytonk Monkey: Do you have pic of your box mounted in the trunk ?