Well, in the end I paid $36 for takeout sushi for two people... which is, I guess, not an unreasonable price in America. $77 is getting pretty high even for a big coastal city, although I'm sure there are people who happily pay that.
Yeah, if I went to my local grocery store which has a sushi counter, for two people I'd be about $12/main + $6/side (e.g. seaweed salad or Gyoza), so ~$36 for two people. I'd generally pay more in a restaurant even for takeout.
For 2 people, expect sushi delivered to your door in SF to be $50-100 depending on how hungry you are.
Keep in mind 2 pieces of salmon belly nigiri will be $6-9 depending on the restaurant. And this excludes taxes, driver tip, delivery and service fees, etc.
How much would it cost where you live?