From my experience it takes more than just the Dev to get a coin listed and the coin grow. It's important the community get's behind this project and tweet, comment on FaceBook, vote the coin on exchanges and keep asking on troll boxes when the coin will get listed. Remember Vote! Exchanges take note of tweets. Major exchanges look at innovation.
I have been lucky enough to see different coins grow from the beginning and to see the same community members help these different coins. These members will make themselves known if not already but the way they find new coins is through social media.
Interesting insight. Rome wasn't built in one day

To get listed on smaller exchanges, it often costs about 0.5 - 1 BTC. Listing at top exchanges like Polo will take time and a lot of community buzz/efforts
It is not just getting onto exchanges but advertising as well. But yes you do have a point.
Maybe having a Slack account for the community to discuss the coin and give new ideas. There is a wealth of knowledge that can be discussed through this channel. As there are always like mined people discussing Sumokoin from coders to "great ideas" people being thrown around. Having different channels such as "mining" or "development" can further focus the team, (if you want a team). I know I would like to discuss what I think the price of Sumokoin should be based upon what it costs me to mine.
Ideas such as how to raise money to list on exchanges or advertise could be disused here. Three words to remember: Advertising, Advertising, Advertising. People can't help this coin or even know about it until they hear. Maybe getting the wallet gui sorted first to make it easier for people as I know you are working on it ;-)
I do have an idea about raising BTC for listing on an Exchange and that is donations. It would be a good idea to get a view on where the community would like to Donate their BTC. This is actually very hard to get people to donate when no-one has made a profit so not really recommended now.
I know when I start to make a profit in a coin I always donate to various projects, especially with a coin that has a good concept like this one. And the potential to grow more. I stick with a coin when it has a good community of people. You have already attracted some bigger miners. When you attract traders and the like these people are known to just pay for adverts for the coin just to boost the price. More people, higher price. They do this because they hold lots of coins. They like to research and Slack is a great way to get a feel of the community (or even here on bitcointalk).
Maybe some someone wants to buy SUMOKOIN from you with the premise and you can use that to list on an exchange. Or maybe thats a bad idea? What do you guys think? Ideas?
People will be interested in this coin. Just get the word out. Social media will get the right contacts to forward Sumokoin.
Just my opinions again :-)