Well, now that we have 4 yougin's most (really all) disposable income goes to those little lovelies. That said, long gone are the days of my weekly lunches at Nobel Fish in Clawson, Michigan (a quaint little 'burb outside Detroit), which is arguably one of the best sushi places anywhere.
Anyway, from time to time my eldest daughter (she loves california makki) will ask me to buy one of those plastic containers of sushi you see at your local grocery store, e.g., Kroger, Tom Thumb, etc. And from time to time I will buy some nigiri on impulse for myself. I would get frustrated when I didn't have the ability to create my typical little bowl of soy sauce, ginger, and wasabi, until I developed a compromise. Here's how...
First, surrender yourself to the fact that you just bought sushi in a grocery store and don't worry if the toro is "sushi grade." Just go with it. It's an adventure. Heck, if you even laid down the cash for the raw food, you must have been jonesin' for it. That said, this technique really only works for makki, so I skip the nigiri.
Second, grab a few extra packets of soy sauce, or have a bottle of low sodium Premium Soy Sauce that is Sushi/Sashimi grade (NOT Kikkomans or other "American" soy sauce that you add to your rice dish at the local china bistro... they're not the same.)
Third, don't worry about chopsticks, unless you're a purist. I personally eat sushi with shopsticks and pick-up only hand rolls, but it's a personal preference that, again, I surrender myself to eating the entire plento box (plastic bento box. My own word. It's a portmanteau of sorts) sans chopsticks.
Fourth, with the makki all lined-up like little soldiers, open a first packet of soy sauce to then drizzle on top of the individual rolls, unless you have plenty of soy, then liberally apply.
Fifth, with a spreading utensil, like a knife or finger, dab or spread a minimal amount of wasabi (provided in a clump within the plento box) on each individual roll.
Sixth, estimate how much ginger they gave you (I think the margins on ginger are too low, so they tend to skimp on this) and place a smallish yet visible piece on each individual roll.
And Seventh, consume the makki you just spent $5.95 on an impulse.
Not too bad this way. At least it is less messy, quicker, and somewhat more enjoyable, than the alternative. Good luck, and happy eating!