$100 is dirt cheap for boots.
Honestly, I don't bother with anything in that price bracket. Not because I'm 'Mr Moneybags' (I'm not, believe me), but because stuff in that price bracket is usually just a waste of money. I'm actually too stingy with my money to waste $100 of it on something that wont last.
A $100 boot will likely just be glued together. It's a dirt cheap way of making a boot, and it gives retailers something to put on their shelves. But when the glue holding the sole on fails (and it will), that's the boot done; they're only good for the bin.
Spending a bit more, you get a boot that actually lasts, which makes more sense financially. A Goodyear welted boot, for instance, has the sole attached via a stitched welt, which means the stitching can be re-done and the boot resoled. Entry level Goodyear welted boots (Thorogood, Red Wing, etc.) normally start at more than double the $100 figure, but they'll probably last more than twice as long to begin with, and can then be re-soled multiple times too.
Obviously there are diminishing returns at play (a $300 boot will be better value than a $100 over time, but a $500 wont give the same jump in value relative to a $300 boot), but spending $100 on boots now will just leave you needing to spend another $100 again in the not-too-distant future. Spending a bit more now will pay for itself over the life of the boot.
It's a classic case of 'buy cheap, buy twice'.