Looks good, but I think you are going to run in to problems with the sand and rock. Most "betta"/"goldfish" bowls are bare bottom with plastic deco. I think the rock/sand will over time build up waste, or more time will have to be spent cleaning.
The time spent cleaning the rock/sand may be worth the trade off in having a saltwater fish.
The other problem I see is making 2.5gal of saltwater every day, is it worth the time?
(for me yes, others maybe maybe not)