So I finally sat down and calculated the projected costs of this project, taking into account the ideal number of characters and backgrounds I would want, as well as other assistance such as music and programming help. It turns out the cost will near $10K.
This figure does not include the 3 entire dungeon levels which I already tossed aside (or merged elements into the existing dungeon plans), as well as a dozen or so planned music tracks which I decided to forgo in favor of more remixes. In other words, that figure is the result after the cost-cutting. I also decided to give up event CGs and plan to re-use existing backgrounds for most everything (using efficient compositing to make sure no two screens look too much alike).
It's high for a hobby project, but this is nothing in comparison to some hidden object games which rack up art bills in the tens of thousands. I have about 5 people I'm contracting, and if each person gets about $1200-$2000 worth of workload, it's not hard to see why the bill will tally up like that. And in fact I still think that they're being affordable with me because I'm an unknown beginner game-maker. I've seen the costs other people charge for other work -- and they are still within the bounds of 'indie' level -- and they're definitely unaffordable given my personal budget. I feel lucky with the level of talent that I have, so what I can do is to make the best game I can make.