Well, you will find high-quality writers as well as crappy ones at both ends of that spectrum. But yeah, logic say the more you pay for an article the highest its quality should be.
But this isn't always the case. So, stick to my guidelines, contact as many writers as you can, evaluate their samples, check the comments from the last 10 pages or so and take your own conclusions.
Something I like to do is PMing guys that have recently order from marketplace writers and ask privately for their feedback. I make sure, they haven't posted any comments on their respective BST.