I thought about buying that also, but ended up getting a kit from ebay and buying a MS170 from the local dealer.
I'm not sure if you're new to this or not, but I'm 100% beginner. The 170 seems to be working great for me and I can afford to replace it once for what a 543 cost. I go slow so... While I don't consider myself a weakling, I'm surprised at the new muscles I'm using. Where am I going with that? Well, I'd consider the weight of the saw to be a pretty important factor. That said, the 543 seems to be pretty light for it's HP rating.
FWIW....I got my cannon bar, chain, drum and rim from ebay for a little over $100. Walked into the dealer and had it mounted and running in under 10 minutes. I'm about $300 and change into the deal, and I can throw the Stihl's original bar/chain back on and pedal the saw if I get bored. I figured to back out of the 543XP I'd need to buy a bar and chain or find another carver that wanted one.