The .15 fee is pretty reasonable. I may even consider paying it for a sizable bounty in return.

Here are some of the other exchange fees I'm aware of from prior coin campaigns I've helped with:

Cryptopia.co.nz: Cost is 5,000,000 of their DOT coins to get listed, or about $200,000 USD
Coinexchange.io: Last quoted price from them was 4 BTC for a listing
CoinsMarkets: Only .5 BTC to be listed... but I'd be wary for now with all of their technical issues
Bittrex.com: They don't charge a fee exactly, but the process is long and you'll want to wait until you have a solid, established coin.  They're very picky. There are co-marketing opportunities (if you're incredibly lucky to be chosen) in which you contribute some funds for your launch.
Binance.com: After the coin takes off, enter their monthly contest. CryptoRand recently tweeted that the winner has to kick in up to $1mil USD to be listed.  

Keep an eye on Nova Exchange. They are supposed to be opening up their doors again in the next month or two, under new management.