Unless you exclusively buy high-end designer fashion or create clothes for artistic expression, you're not really better off making your own clothing. Most of the time, fabric costs are higher than clothing costs, and when you factor in thrift stores, forget it! Instead, use your sewing skills to repair clothes instead of throwing them out.
2. Cream Cheese
Making your own cream cheese is a process that takes an entire day. (Admittedly, you won't be actively making cream cheese that entire day, but still.) When you factor in the cost of tracking down that erstwhile staple rennet, you're better off buying. Wal-Mart has a 12-pack of Junket brand rennet for $26.12 (and you still need milk!), pushing the per-recipe cost well over the $2 that brand-name cream cheese costs.
Home repair and woodworking forums online are havens for people who prefer making things to buying them, and even they tend to admit that cabinets aren't worth the effort. By the time you pay for materials and hardware, you could’ve already had someone else make them. Many people actually recommend buying cheap cabinets from IKEA, using what's stable, and customizing what isn't. Even Pinterest isn't crazy enough to try and make cabinets from scratch. Basically, every DIY involves customizing prefabs.
Lots of foods are cheaper to make, and you'd be surprised how many sauces, seasonings, and even vegetables you can get away with making or growing. But some vegetables are too labor-intensive or require too much equipment or don't yield enough to be worth growing on a small scale. Potatoes are a good example. Even if you use the space-saving method in this link, you're still spending $70 for a 50-gallon barrel. On top of that, potatoes are very water-intensive and so cheap at the grocery store that it's just not worth it to most people.
5. Tomato Paste
You can spend all of your time and energy turning a ton of tomatoes into a small amount of paste, or you can buy a can for a dollar. Better yet, buy a big jar of it for a couple of bucks. It's fresher, more versatile, and more cost-effective than buying ten pounds of plum tomatoes, which is going to set you back around $15 every time. (And that's ignoring the cost of olive oil and effort.)
Heavy-duty fabrics that curtains require are even more expensive than clothing fabrics. Even if you find fabric on sale, you're still probably going to pay per yard what it would cost to just buy curtains outright—and that's ignoring the kinds of deals you could find getting used curtains. At absolute best, you could get solid color fabric for around $13/yard, but that still can't beat an inexpensive pair of prefabs.
Yes, you can make your own pasta at home for the cost of a handful of flour and a couple of eggs, but this is one of those situations when the time factor should play a part in your decision-making. A bag or box of pasta usually runs at about a buck. Sure, you're only spending pennies on flour and eggs, but the time and effort required mean it's not worth it. It's great to have a pasta recipe tucked aside for special occasions, but know when to use it and when to buy.
8. Light Bulbs
So, you want to make your own light bulb. There are all kinds of light bulbs for all kinds of prices, and buying in bulk saves you money. But let's call it about $2/bulb (that should cover a safe range from cheap to decent)—and let's be honest, hoping for more than "decent" out of a homemade light bulb is a stretch. You're gonna need a mason jar, so that's a dollar right there, 10" of wire, call that about 7 cents, 4 cents for heat-shrink tubing, and more for JB weld, 4 screws (plus however many you waste failing to drill holes in them), washers, graphite filament, CO2 to flood the bulb with, and more... All we’re saying is, consider your options.
Shelving is an important part of any home -- from bookshelves to garages, you can never have too much storage. Still, by the time you've spent $120 on lumber, you haven't really saved any money. Will this hold up better than plywood? Probably so. (Unless you used cheap pine, then it's kind of iffy.) If you’re looking to go cheap, buy your shelving.
You can buy a mass-produced, factory-made quilted throw for about $40 on Amazon. Can you make a higher-quality one? Absolutely. But fabric, batting, and notions all together are going to run you about $40-90. Plus, that's assuming you already have a sewing machine and a rotary cutter and aren't charging for the time you spend sewing and screaming as you thread the bobbin.