I'm interested in getting the new damage deck and the BB-8 card. ... but, ummm, currently my wallet can't afford the new Core set. (Okay, actually I'm just not interested in anything in there currently outside of those two things.)
I don't see a way to order just those cards ob FFG website. Is there another way?
eBay but the prices are seldom worth it.
Yeah, the Bay of e or trading are probably your best bets.
I believe Team Covenant sells individuals, but they're rarely in stock. Anything worth buying is gonna cost a bit
I wanted some additional dice recently - just bought another core set as Amazon has it for $24. Dice alone are $8. $16 for the rest of the set seems like a pretty good deal when I looked at it that way.
For those items you might as well just go for the full $40 US or your regional equivalent and get the new core set. 
As much as I wish that FFG would sell the new damage deck separately or update the classic core set, there is no indication that FFG would even do that. 
Maybe after worlds some players would put their damage deck up for sale as they probably plan on or already have the TFA Core set. Until then best bet is just to go for the TFA and you are not alone in your unhappiness with the way it was marketed and sold. 
Proxy until you can afford it.
Or find a way to buy the TFA core set, and then sell all the parts you don't want.
Sorry, you're screwed.
I read that people are willing to pay good money for kidneys .... you have 2 of them so you could sell 1 
This maybe one answer and its on this forum.
https://community.fantasyflightgames.com/topic/105906-the-big-x-wing-trade-thread/
Split a core set with someone, eg someone just starting the game.
Trade threads on facebook work well for alt art but also for other cards:
North America:
https://www.facebook.com/groups/northamericanxwingtradeandsell/
World-wide: