Visit the frozen food section and fill up your shopping cart.
"Cooking for one" doesn't really make much sense financially. You really end up wasting a lot of food. It either goes bad before you can eat it, or you end up cooking on one day and eating the same thing for an entire week. If you don't eat it fast enough, you end up throwing it out anyway.
If I want a meal that isn't out of the freezer, I usually go out.
Prepare a decent amount of food and then freeze it in single serving packages (zip top freezer bags are great for the freezing). It may take some up-front investment to get yourself a variety, but then you only need to restock a meal or two per week. Freeze the bags on a sheet pan and they will end up in a better "stacking" shape.
Some favorites:
Taco soup:
hamburger (browned)
tomato juice
corn
pinto beans
taco seasoning
onion
(really, anything "taco"y that you want to throw in)
Serve over fritos corn chips with sour cream and cheese
Shepherd's pie:
hamburger (browned)
green beans
tomato soup (combine these together, put in a baking dish)
Cover with mashed potatos (the instant kind works just fine for this - the Potato Pearls from the dry pack cannery, even better)
cheese
Bake at about 350 for 20-30 minutes (this one won't freeze as well in zip top bags - you'll have to find some freezer friendly tupperware)
Curry:
You can find a curry sauce mix in the ethinc food isle at the grocery store (or, at least I've found it in Virginia and Utah, I would imagine it's pretty much everywhere). It kinda looks like a chocolate bar when you open it up. Follow the directions on the box (we usually put in carrots, celery, green peppers, onions, and chicken).
On a blog my wife reads there was a recipe for burritos that can be frozen - I'll see if I can find it (this recipe was huge - it makes 24 burritos, I think).
There's always your basic hamburger/tomato sauce/elbow macaroni stuff. Add whatever sounds good at the time (I usually add corn, tomatoes, onions, and probably more that I can't think of at the moment).
Canned/bottled pasta sauce works pretty well if you aren't making a whole lot. Cook up some noodles and just poor in the already prepared sauce. Add some kind of meat - or anything else you really want.
I've got some more, if you want them, but they will require more work (and I'll have to look up the recipes cuz I don't have them memorized). Let me know.