I was in a similar situation as you. I'm 15 and I am already a bit over 6'2" (my father is 6'6" and brother who is 20 is 6'7") and I wanted a nice road bike. I originally intended to go with a cheaper bike around $400 but quickly set my mind on getting a nice brand name bike and found the Trek 1.2 for ~$750. I got a magazine from the local bike shop and after reading it I found the 2.1 was indeed more expensive but had a very nice frame and components (I had done plenty of research previously) and decided I could splurge and get it. I did and I haven't regretted it yet (despite owning it a whole 2 days).
The point is, find something nice, and then go up a model. You won't be disappointed! Also, the bike shop was very helpful and fitted me and took my relatives height and my age into consideration and I waled away with a 60cm frame. It is a little bit big now, but I'll certainly grow into it and I should have no problems with it for years to come.
Just save up and get a real road bike. Ordering online is the best way to get turned off from biking. You save a few bucks but you have to assemble it ($100 worth of tools and a $100+ repair stand) and you need the experience and often the parts get a bit beat up when the bike comes 90% assembled.
Cannondale, Trek, Specialized, Giant, and many others make great bikes starting at about $700 for a nice bike and working up to over $10,000.