I upgraded very quickly mostly because I knew I wanted a triple AND because I had some credit built up at another bike shop in town, so I didn't have to dig a whole lot deeper into my wallet on top of the purchase price. Otherwise I probably would have stuck with the 105 double and upgraded slowly. (I doubt that I would notice the diff between 105 and Ultegra at this point in my limited cycling experience.)

If you're confident buying bike parts online, you could keep your eyes open on geartrade.com, ebay, and other websites that knowledgeable TE'ers use. My BF and I nabbed one brand-new component for my Fuji on geartrade.com for about one-third retail. Of course, it was just good luck/timing that the part was listed for sale right at the time I bought the Silhouette. I'm now keeping my eyes open, casually, for a deal on a handlebar.

Whatever you decide, enjoy your new bike!