Aldi (USA) use to be
extremely cheap, but its selection was limited. For example, in 2008, it offered two varieties of bread - white, sold at just a dime per loaf, and wheat, sold at just a quarter per loaf. Today, there's over a dozen varieties of bread, and prices are slightly less (sometimes slightly more) than
Walmart. Produce is another example -- in 2008, there was a handful of local, in-season offerings (as well as staples including apples and bananas) that were cheap. Today, there's a huge variety, including organics, and prices are higher.
Aldi limits its loss leaders to milk, eggs and select produce items. You won't find Coke or beer on sale here.
Most of its non-perishable items are priced slightly less than Walmart, but many of its perishable can be higher. If you shop sales, stock up, and use digital coupons at your local traditional grocery store, you will save more in the long run than you would at Aldi. Another thing to consider is that the quality of Aldi's meat and produce can be very disappointing. Thankfully, it offers a great replacement policy, but some staff is ignorant.
A popular misconception. Years ago, the brothers that founded Aldi split the company in half; the two separate companies continue to operate today. One of those companies expanded "Aldi" into the USA. The other acquired Trader Joes.