Its no secret that I like myself a good deal, I mean who doesn't?! I've actually been known to walk away from a dress or top because $30 is too much! But that's not to say that I haven't made some pricier purchases over the years, because I definitely have. Its just a matter of knowing what items you should spend more on and what items you shouldn't. And those items will probably differ from person to person because we all have different styles and different needs.
For instance, someone who doesn't like carrying a purse/bag (DEFINITELY not me!), probably wouldn't (or shouldn't) spend big bucks on a designer bag, whereas someone like me who has an obsession with purses and bags, would.
The basic rule is to generally spend more on the pieces you plan to wear or use often, such as purses, bags, shoes or outerwear. These are items that will get used more often, hence why getting higher quality (which usually equals higher prices) is worth it. It might have a steep price tag, but you're "price per use" will be lower the more you wear/use it.
For items that aren't basics in your closet, especially if you're trying out a "trend", its almost always a good idea to look for lower priced versions, so you can get your fix, but not feel bad if you only wear it once.
Scrolling through many style blogs or Instagram style accounts, you'll see a lot of "mixing" of high end designer items and lower priced items. Even celebs do it; its not uncommon these days to see a well known celeb sporting an item from say Forever 21, and accessorizing with a pair of designer shoes and killer jewellery.
And that's something you can do as well: if there's an amazing purse you have your sights set on (I have like 5 on my radar) or a pair of pricey shoes that you know you'll have on repeat, go for it. Pair them with a fun dress from H&M or jeggings and long flowy tunic top from Forever 21, and you'll have a perfect high/low look!