Buy something that is issue as it will be made quite durable compared to aftermarket items. Having said that, there are some manufacturers of high quality BDUs (TruSpec, etc), but you can often get surplus issue items for less money... I wear Russian Flora.
The propper camouflage IS effective at under 100ft if you use your suroundings properly. Movement is what often gives a persons' location away. Move slow, use your suroundings, and use shadows if possible... The reality is when an opponent is laying in wait he/she will see you long before you are within AirSoft range due to your moving and him/her not.
As mentioned already, different camo patterns for different seasons... I need to get myself something for fall next season, but what I did this year at the one site we play at is stay near the coniferous trees that were mixed amongst the deciduous trees. At one of our other sites it is all decidous trees, so a bit harder, especially as the leaves turn and fall off...
Call sign: Usurper