I have recently gotten into playing and after reading some threads from here and BoardGameGeek, I have bought two more core sets and each of the deluxe expansions out (waiting for Kings of the Sea reprint). What I would like is to have a basic, balanced deck for each of the houses and a more "complex" or advanced deck for each house so the group won't become bored with seeing the same deck over and over again.

Is this something that would be even possible or would I need to buy more to have a good set of decks for everyone to use?

You would definitely need to be switching a lot of cards back and forth between the basic and advanced deck for each House. If you have the box expansion for each House, why not make the premade decks that come listed in each box? They should be relatively balanced. You should be able to make a basic burn/attachment deck with 3x Forever Burning, 3x Flame-Kissed, 3x Bones of a Child etc, and a basic gold+draw deck with 3x GTM, etc, though there isn't much kneel in core Lannister other than Enemy Informer. Those two would probably be weaker than the others but would benefit from some of the plots in the deluxe expansion; Targ can use Threat from the North and Marched to the Wall, for example. Targ box will be here soon.

Yeah, I think the Core Set "as is" decks are pretty basic and, at the same time, offer quite a bit of variety. The tradeoff is that there isn't a lot of efficiency...one game you might be playing with a bunch of dragons, the next you might have a bunch of guys with attachments. In terms of variety for casual play, that's probably a good thing.

If you're talking more about the variety of a "rush" versus "control" versus "combo" styles, then you probably will need to invest a bit more into duplicates (extra Core Sets, etc.). In this case, you really need more cards to give your deck consistency. The problem is that all of these different deck types will still use some of the same cards...for example, resource-providing locations are necessary in any kind of deck, and cards like Forever Burning are a staple in any Targ deck (whether it's "control" or "aggro/rush").

If you want to get the feel of more customized decks without spending much more though, I would start with swapping around Plots. Making changes to the 7-card plot deck (for example, giving 2-3 houses a copy of "Valar Morghulis") will make a *big* difference in terms of play and how the games feel, without a major investment. In fact, you could get 2-3 copies of each plot, pile them all together, then let players pick the plots they want. That way, you can keep the draw decks unchanged (or only customize them 1-2 times), but keep the game very interesting.