Suggestions about making grass in 3D

[deepak.froggy]

Hello guys im using 3DS MAX and i need some grasses of varying height from (10 cms to 30 cms) in my 3D scene to spread over a very large area. Im confused whether to use bump maps or model them by myself or is there any plugins or script to create grasses of varying color and size??? and as it is a very large area i dont want to get my poly count very high (moderate poly count is ok with me)... plz suggest me some ideas regarding this... thanks in advance