We're big homestead gardeners and have done a ton of preserving of all kinds. Here are some takeaways we've come to.
1. Freezing is way easier, faster, and cheaper than canning, if you already have a freezer with space, and if you're going to consume the food within a few months. Canning wins if you're trying to preserve shelf-stable food not subject to power outages for 1-2 years.
2. Preserve foods that you actively and regularly eat. MANY of us who grow large gardens and have done a ton of preserving find that after a few years we are basically canning tomato sauce (sometimes salsa), jam, and maybe one type of special pickle. In other words, a few key staples. We've all thrown a lot of other stuff onto the compost pile that just never got eaten.
When you're buying produce to preserve this is especially true. We buy some very favorite things in season that are delightful to pull out during the winter: extra berries, sweetcorn, peaches... which leads to:
3. Preserve those things that are expensive or not tasty when not in season locally. There's no point in preserving potatoes, garlic, onions, carrots, etc. Those are cheap to buy all winter. Strawberries and many other fruits that are picked at peak ripeness and frozen are often cheap and easy to procure through the winter and not worth buying to freeze. I buy bags of local, frozen blueberries on sale in the winter for far less than the cost of fresh, even in season.
4. Don't preserve things that last a long time without preserving.
Apples would fall into this category for me. Apples are a storage crop that will last months in your fridge, or even in a garage or other cool place (with the right humidity, but this can be faked). I preserve apples when we have hundreds of pounds and I know I can't eat them fast enough. Cider is my preferred method ;)
In your place, I would buy lots of yummy, cheap apples and throw them in the fridge and maybe throw a box outside on a balcony until it starts to get frosty. If some start to go bad, I would make pies or small batch applesauce at that point. Dried apple slices are super easy to do, tasty and economical, and you can make apple cider vinegar with the peels and cores. Yum!
If you specifically LOVE applesauce and want to make your own, then by all means buy cheap apples for that purpose and enjoy the deliciousness. :)
Hope that helps!