You can get everything you need and then some buy just buying any entry-level drop bar road bike at the LBS. Shimano 2200 (yes, 3 levels under 105) works totally fine, despite a few hiccups here and there. My $650 entry level road bike is capable enough to keep up with the local "A" hammerhead rides (as long as I'm in shape) and not have any handicap. Even the weight isn't bad - you won't be 16lbs light, but you'll be 19-20 easily for the full bike.

That said, 105 shifting is overall crisper and more reliable. Whether you feel it's worth an extra $400-$600 for that perk is a different story. For sure, you can ride just as fast on Shimano 2200 entry level stuff as you can with 105, and from my experience, it doesn't wear out appreciably faster too. (Plus the parts like chains and cassettes cost half as much.) My 2200 triple isn't perfect, but has required pretty much no maintenance in the past 3 years. It gets a teensy bit glitchy on the extremes but that's not unusual for a triple. It's never slowed me down or given me a headache.