We have a knife at home that we've used for close to twenty years. And that's still the knife that we prefer to use. It was easily 10x the price of a normal knife when I first bought it.
So, really, the Cheapest item is not always the best when you calculate in terms of how much use you get out of it.
Think about it this way:
I could easily buy a pair of sneakers for $10, but I wear it once, and then throw it away because it's too uncomfortable. Costs me $10 the only time I wear it.
Or I could buy a $100 pair, and wear it 100 times before it wears out. Averages out to $1 each time I wear it.
Great questions to ask yourself when shopping:
How often will I use it?
If it's something you use every day, it's worthwhile looking for something that's of better quality, and will last longer. But if it's something that you may only use for a short period of time, like a pair of sunglasses that will go out of fashion next season, try looking for something which costs less.
Does it have the features I need?
For example, we have a $40 digital camera which we hardly use, because we still print out our pictures, and it doesn't take pictures that are good enough for that. But our $500 camera? We bring it with us everywhere we go!