Susan, my friends and I have girls nights where we make tons of sushi. It's a lot of fun since we all like to cook, and if everyone brings one type of fish, a few vegetables, etc. the cost is spread around and it's pretty inexpensive. Some grocery stores sell a few of the ingredients, but if you find an Asian foods store you can get all of the ingredients inexpensively. I live on the coast so fresh fish is everywhere.
You can buy a sushi kit that has bamboo rollers (look like a small square placemat), a rice paddle/spreader, and some chopsticks and things, but in truth my friends and I don't use the rollers and the rice spreader that came with my rice cooker is better than the one from my roommate's sushi kit.
I recommend getting everything prepped and then assemble the rolls.
Sushi - yup, they just sell that in sheets. The big (8x8"?) square sheets are easier than the half sheets to start with.
Rice - Sushi rice is short-grain rice, which means it gets sticky when it's cooked. You can use a rice cooker or cook on the stove. Once it's done, dump it into a bowl and mix rice vinegar in generously. I'd guess about 1/4 cup to every 4 cups cooked rice, perhaps. This helps make it spread better. You sort of have to trial-and-error to learn the right texture. I think I once saw brown sushi rice at a health food coop in the bulk bin, and I kick myself that I didn't buy any. Most sushi rice is white rice, which of course has a high GI and is a refined carb.
Veggies - We cut up cucumber, green onion, avocado, sometimes peppers, carrots, whatever you like.
Spicy sauce - Mix mayo and hot sauce (I forget what brand of hot sauce we get - I don't even know if it has any writing in English on the bottle) to desired spiciness.
Sesame seeds/black sesame seeds - Lightly toast in a pan on the stove. When you can smell them, they're done. Keep the pan shaking while you're making them.
Wasabi - get the powder, not the pre-mixed stuff in the tube. Mix in a little bit of water at a time until it turns into a paste. Do this first, then flip the bowl over (to exclude oxygen) and let it develop its flavor while you work on other things.
Soy sauce - self-explanatory...
The fish - here are a few options - get very fresh fish!
Raw tuna, salmon, other fish - Get sushi grade tuna and slice into thin strips with a very sharp knife or fillet knife
Crunchy shrimp - Most stores sell tempura batter. You mix it w/ water according to package directions, and fry in a bit of oil. If you have extra batter you can just fry it to make crunchy bits to put in the rolls, or to munch on...not that I would ever eat fried dough, it's so bad for you...
Scallops - Lightly saute the scallops in minimal oil, cooking spray, etc. If you have sea scallops, cut into little pieces. Cut bay scallops in half. Hard boil a few eggs (~3 for a pound of scallops, which will make a lot of sushi), chop the yolks, discard (or eat for a snack the next day!) the whites. Mix the scallops, yolks, and spicy mayo/hot sauce together.
Soft-shelled crab - You can also tempura-fry a whole, small-ish soft-shelled crab and lay the whole thing in a roll. I don't care for it, but my friends say eat it the night you make it, b/c the texture is bad the next day.
Eel - My friend gets it already barbecued at the Asian foods store, and she just adds a little eel sauce, which is sold by the bottle.
Roe - again, if you can find it and care for it
Crab - You can get real crab meat already cooked. I think the fake crab sticks taste horrible (this is what's in most California rolls, at lots of sushi restaurants) and don't bother with them.
Assembly: you take your sheet of seaweed. Spread rice on very thinly with the spreader. You can use a flat spoon, too, but it's a bit more awkward. At one end, lay strips of the veggies, whatever meat you want, the spicy sauce if you want, roe, sprinkle a few sesame seeds, etc. Don't fill it with too much - you want to be able to roll it! Starting from the side with the filling, take the corners of the sheet and roll inward to form as tight a roll as you can. When you get to the end, wet your fingers to help seal the seaweed seam. Cut into 6 or 8 pieces with a really sharp knife.
Inside out rolls have the rice on the outside. These are a bit harder to roll. You spread the rice, flip it over, and then fill it and roll as above. Sesame seeds look pretty on the outside.
Then there are those smaller rolls (that's what you use the seaweed half sheets for) that have rice on the inside, and fish on top, and look really pretty... I'm working my way up to that. I don't care for them as much, really!
Dip in soy, wasabi, whatever you like, and enjoy! It takes some practice to make it look pretty, but even if it doesn't look pretty, it still tastes good. Also, it definitely takes time and about every dish in your kitchen. You can eat leftovers for a day or two (careful with the raw fish), but as I said apparently the soft-shelled crab makes a gross leftover. The rest are delicious for lunch! Have fun!