I can't believe no-one has brought up fermentation control or buying bulk extract...
The two upgrades I would recomend for you are:
1. Get a controlled temperature fermentation figured out.
2. Ensure you are pitching a proper amount of good healthy yeast into a good wort environment.
3. Buy DME in bulk (purchase some air-tight containers from US Plastics) and save a crap load of mulah.
4. Buy bulk hops from hopsdirect or other source.
5. Start taking meticulous notes. I recommend braukaiser.com logbook.
6. Understand the limitations of extract and learn to formulate or use recipes that utilize the advantages of extract while avoiding the (relatively few) limitations.
7. Assess your beer. Are you happy with it? If not and your realize that the thing you would change about the beer can only be accomplished by cutting out the extract, then consider going AG.
That is the progression I would recommend. I love AG brewing for everything it offers. Tons of science and nerdery. I rarely brew with a single infusion mash schedule and am always tinkering to try and manipulate aspects of my wort. If that isn't something you are into, whats the rush?
I still brew extract+grain batches. I normally do them while I am brewing an AG batch. I can do extract in my sleep and the beers turn out fine. I use extract for super simple stuff like my American mild. The other factors have a larger affect (in general) for new homebrewers that the source of the wort sugars.
Above all, do what you want, this isn't your job. Have fun
