Re: Front wishbones, what are my options?
The only problem with poly bushing wishbones is that it's expensive and even though the bushes should out last the car, if the ball joint on the wishbone gets worn/knackered you have to replace them anyway. I'm in pretty much the same boat as you at the moment, but my knock is my track rod end, nothing to do with the wishbones(after replacing uppers/lowers & drop links). My knock happens occasionally on acceleration, braking and turning it's just where the track rod end hits the hub where it mounts into.
You're looking at around £80-100 for a GTA front ARB and then about 3-4 hours fitting, so it's going to cost you at least £300 or so I'd guess with the wishbones too. I'd pop to a specialist if there is one not too far away and get them to diagnose where the knock is coming from unless you fancy having a poke around yourself. It'll save buying/fitting new wishbones/ARB unless they are shot.
I'm going to get the GTA ARB and attempt to fit myself as I need to take a look at replacing my steering rack too whilst the sub frame is off/down. Replacing the wishbones youself isn't difficult, more frustrating than anything else as it's not easy getting everything lined up and bolted back on. Helps also if there are two of you. Don't forget to get the tracking checked after the wishbone change too.