if you count in man-hours, then yes it's into the 100ks.
going from the single indie developer perspective,
assume you pay yourself $100/hour game takes 4 months to develop total cost is 100$ * 120 days * 10 hours/day = 120,000 $
the cost for game assets have not even been included!
but no indie developer I know take these costs into account. Who actually cares about sweat dollars? If two-three people sit in room, code+draw for 4 months straight taking ramen noodles, launch and make millions off the game on iOS, they're not going to tell you "We spent $120k of our own money+time". Instead they'll say "We spent 4 months furiously making the game, living off ramen noodles in mom's basement"
in summary, the development cost could be either be close to zero, or $100k.
if you're hiring a team, yes prepare to splash $100k, but if you go indie, get some good game dev friends, and absorb all costs!