The bike is selling for $850 brand new, so you decide if this is a good deal or not. If it was me, no and I would buy new. If you don't know much about bikes, a new bike will come with free tune-ups, the shop will size you correctly and you may even get discounts on accessories. I have heard the complaints that the Trek CR has lesser components than other builds, but rest assured the components on it are pretty good.

The 7.3 FX is a complete different style of bike. It is a great bike especially if you like that upright position. I find this style of bike preferable for commuting but that is just me. I hope you find something you like.