What are they charging you for it? Is it a 2013 model or a leftover 2012? If its a 2012 call every shop around until you find one that has it in stock, they will take a couple hundred bucks off of the price to move it off of the floor; especially in October/November. If its a 2013 its really hard to get a good price on it especially on a special order. Any dealer has to pay $30-50 bucks just to get a single bike shipped to the shop. You can't really negotiate on the price of the bike but it isn't unreasonable to ask for more of a discount on any accessories you buy because the margins or profits are higher on those.
The new Tiagra is really nice and is up to par with the 105 group. 10 speed and STI shifters.. you will be really happy with it. Cannondale is a great brand, I would just suggest test riding a comparable model in a few brands; Trek, Giant, etc. You get the most bang for your buck with a Giant, but I test drove one and it just hurt.. I hated it, but there are a lot of people that swear by them.
Hope that helps..