Just got the core set, mostly looking to play casually with my wife as my main opponent. Any tips? Expansions to grab? Not looking to go crazy but things I can be on the look out for?

A second or third core set will greatly enhance the flexibility of the decks you can build.

Any affordable options? Cause that will never happen.

Actually, a second or third Core Set will have a bigger impact on your decks across the board than any other purchase (Deluxe Expansion or Chapter Pack) you make, and it's a better deal (per card) than the others as well.

Check out eBay -- some folks are getting out of the game and selling off their stuff for a lot less than retail...

Play with the core set and look at the factions, the houses that interest you most. To play the game to its fullest two additional cores will allow you and the ones you are playing with to use any options you want to the fullest. The deluxe expansions will let you focus on specific houses (Wolves of the North - House Stark, Lions of Casterly Rock - House Lannister, Watchers on the Wall - Night’s Watch) The Chapter packs are evenly distributed across all houses, you get 2-3 new cards for each house within each pack.

You will get out of the game what you put in.

Somebody's selling their collection for a good price:

http://www.cardgamedb.com/forums/index.php?/topic/34032-moving-a-few-lcg-products/

Any affordable options? Cause that will never happen.

I dont know how much a core set cost where you live but in most of the case in gonna cost slighty more than two pack or a deluxe and you will get more cards for each factions so you should get a second core set.

I'm also looking to get into this game. I would mainly be playing with one other person, and maintaining a single collection for us both. Would a full play set of everything (3x cores, 1x every other product) be enough to consistently support 2 decks simultaneously, or would I have to double up on some of the chapter packs for staples? Used to play Netrunner and that was the nice thing about there being separate card pools.

I would say get what you think you need, print paper proxies for cards that are already spoken for, and experience will tell you whether it would be worth the money to not have the inconvenience of placeholders.