Is display port a requirement?
Checkout this monitor:
http://www.newegg.com/global/ie/Product/Product.aspx?Item=N82E16824009590
slash
http://www.amazon.com/dp/B00G5AH2YG/
5ms response time, 1080p, 27", IPS, 60hz, plus built in speakers. I own the 23" version and can vouch for it.
There is also this monitor:
http://www.amazon.com/dp/B00HY7PAUC/
144hz, 1ms response time, built in speakers, display port, high contrast ratio, etc. and is around the same cost.