Made a trip to Aldi's last night, at what I hoped would be a slow time. I was able to take my time in the aisles, looking for things I couldn't find previously, and writing down prices.

Pleasant surprises:

Nonstick cooking spray (canola-based) $1.29
Turkey bacon $1.89
Splenda, in addition to their own brand of aspartame
Plain, nonfat yogurt
Sugar free "jello" and fat free pudding, in the refrigerated section $1.79 for 6 cups
Fat free "cool whip" 75 cents
Baked nacho tortilla chips $1.49
Mixaid (like Crystal Lite) $1.75
Lite mayo $1.49
Corn tortillas in the bread section, that I turn into baked chips myself, by slicing and baking, 89 cents
Sunflower seeds 39 cents
Tomato juice, large can 89 cents

Some disappointments:
No 1% milk; there's skim but I'm not wild about it
No reduced fat sour cream
No reduced fat sliced cheese
No vinegar besides white distilled (cookbooks say too harsh to be used in salad dressings)
Not much selection in bottled diet salad dressings
No flavored lite cream cheese, only plain
Diet frozen meals limited to "Lean Pocket" type wraps

Still and all, I think I'll find plenty to eat and lose weight. I'll try their diet dressings, and I'll try making some homemade ones calling for lemon juice rather than fancy vinegars.