What US-based developer can afford to work on your project for this long on that pay?
In short, if you don't want to get screwed, you should: first, start paying competitively. That will help you attract good candidates. Second, spend some time vetting them properly.
I know personally, I had a bad experience with a contractor who delivered work after 8 months, when the timeline called for only 1 week of work.
Did you also dispute after 8 months? I would understand if you are willing to cut your contractor maybe a week or two worth of slack. But in OP's case 1-2 weeks difference still doesn't make 1250$ reasonable payment for 2.5 months work.
And if the work was estimated as substantially less, why did OP delay filling the dispute for so long and how is that the web site's fault?
Because of that, I ended up contracting someone else for the work who finished it on time. The originally contractor dripped in the work over the course of 8 months with many weeks delay in communication between each dribble of work done. In the end, they completed the job but I had no use for the work at that point, and obviously won't be recommending them to anyone.