IME with buying bikes, you should definitely go ahead and spend as much as possible to get the one you want -- which is usually double whatever you are thinking at the beginning...lol.

If you get something you think "kind of" works, you'll end up spending more to upgrade it later, or you'll be disappointed and buy the one you really want in a year or so. Then you have the other one sitting in your garage collecting dust.

Just go for it right from the start -- it's easier. When cared for, your bike can theoretically last a lifetime -- well the frame anyway. Well, steel does anyway. Actually eff it - it'll last a heck of a long time.