inb4 loads of Americans suggest you monitors on NewEgg.
Anyway, any monitor with native 1080p and runs @60Hz will suffice. Personally mine cost me ~£110. Here are some suggestions from different stores;
iiyama 23" ProLite XB2380HS-B1 LED Monitor - Black - Scan.co.uk
AOC e2752Vq Full HD 27" LED Monitor Deals | Pcworld (I'd choose this one)
Samsung S24C300HS 23.6" LED DVI & HDMI - Gloss Black (LS24C300HS/EN) - dabs.com