How many hours have you spent on it so far do you think? I don't think I'm all that far in really, no idea how long this game is.
Tombs, glyphs codecs etc about 40 plus hours I reckon. Is there a counter anywhere?
When I started upgrading the villa though I would leave it running while going out or eating my dinner so that you accumulate money while your not playing.
Then just take the money out of the chest and continue.
Also when I first started I did all the side missions but only do one of each for the achieve and then forget about them. You could then do the game in around 30 hours.