What you need then it is a CMS and a template that adapts to it... sort of. There is no perfect template but they may be many that can fit what you need and be close to perfection.
Now, if the template needs some kind of personalization (and I'm not talking about changing pictures or the font size or colors, as many templates provide that kind of features) then you may need to contract someone else to do it and than may cost you a few dollars but that's nothing compared to what would cost you a full design and implementation.
Also, the cost will go higher or lower depending if there's a plug-in or add-on that provides that functionality or not, or if that plug-in needs some rewriting to provide that functionality in the way you want (most of the time, it is not necessary).
You may want to check the major CMSs
All of these are open source and free and have good support
For templates, you may want to visit www.templatemonster.com or www.themeforest.com, as an example.