Have had polly bushes warp over time a and ruin my alignment. Had the Energy Kit on my EG for 2 years never felt right over time and just got worse. Also polly bushes restrict movement were in some cases they need to able to twist.
Racing xs on eBay are a stockist, that's where I got mine from, they'll even price it up per bush for you if you don't want a complete set
That's hardrace btw, much better than a poly bush. Although a hassle to fit yourself.