Just did a DIY attempt yesterday. Bought the ripspeed grill from Halfords £25, there is enough to do this job twice (forgot the other thread mentioned a cheaper version could be obtained from a DIY shop). I got the black one to match the car colour. The front bumper came off very easy. I lined the mesh up with the opening and then cut the mesh roughly to shape and then attached it to the mouth using small cable ties as mentioned on another thread. Tidied up the look by trimming it further and folding the excess over the top of the hole.
Looks good and you can not see the ties as its all black.