It really isn't about the width of the post, but more about the internal structure and thickness of the post/the quality of materials in making the post. If you had a solid piece of steel (through the core), it could probably be 1"-2" wide and never dent, and conversely you can have a 4" wide post that's has thin walls that would dent easily from a street ball. With that said, I have a 2-3/4" post width net, and I shoot regulation pucks at it and it only dents with a very square hit. (I can shoot hard, but not pro hard) Cost about $180 from Hockey Shot. Hockey Shot also makes a net for about $450 that they claim can withstand 100mph shots. Another option is go to local rinks and see if they have any nets that are so beat up that they're willing to offload them. However, in all likelihood that's rare and you'll probably have to put a new net on, which is pretty tricky with official ice goals.