This is my go-to sushi restaurant when I'm craving sushi but can't afford the upscale sushi restaurants that I like (i.e. check out Soul Gastrolounge). The sushi is very good for the price you pay. If you can eat a LOT of sushi, it might not end up being that cheap, but for me, this has to be the cheapest GOOD restaurant I can go to for lunch or dinner. I usually just get a couple sake nigiri, unagi nigiri, and some spicy tuna rolls, and it is under $15. I've also tried their seaweed salad. I've only had that at one other place, but both were delicious!
Here is the full menu:
http://www.allmenus.com/nc/charlotte/41903-ru-sans/menu/
CHEAP!! But it works when you're craving sushi!
Also, I must mention the waiters I've had here have all been very pleasant, and usually pretty fast even when the restaurant is busy.