I don't think you can get Nexus One for 1.5k unless you're looking for 2nd hand unit

if you prefer HTC, for 1.5k you can get either Desire AP set or T-Mobile G2 aka Desire Z which is also an AP set

otherwise you can refer to 41LY45, those are good choices as well

HTC original by SIS is said to come with 2 years warranty. I am not a HTC user, so please confirm this with the phone dealer when purchasing the phone.
I doubt any SE or HTC Android smartphone is within your budget range for the first hand original handset. 

For Nokia, you can try to hunt for Nokia X6 and Nokia C6 if you want a physical keyboard, but both of them are running on Symbian.

if you still want Android at that budget, you can ask around for the CSL Mi 300's price to see if it fits your budget or not.

@fruitie

Sorry about the post.

It's not Android. 
Lol.

Imo, Android is better than
Wp7.

WP7 is still at it's infancy. Not much functionality in the OS just yet.