replacing with new standard rubber ones will really help the stability, polybushes all round will make it a bit squeaky and prone to transmitting more vibrations. It's a personal thing but I've found polybushes good on the sway bar links but a bit noisy elsewhere.
Quadratec in the US do kits and individual components. Over here you can get them from Specialist Leisure and MDG Offroad but you'll pay 2-3 times the US price (including shipping costs).