I find that the key thing to overcome when selling to developers is the extreme reluctance to spend money buying something that they can build themselves. You see,
1.) Developers love to build things.
2.) Developers hate spending money.
3.) Developers undervalue their time.
If your product looks like it would have been fun to build, you'll lose the entire "insufficiently supervised developer" demographic. Those guys will happily spend tens of thousands of dollars of billable hours implementing an in-house version of your thing to avoid the possibility of outgrowing your Free Tier.
I've seen this play out with S3stat customers (which costs $10/month, or three minutes twenty seconds of fully loaded engineer cost), where somebody will spend a week building an in-house version of the service and standing up a server to run it. Nicely done. You'll break even on your investment in 21 years.
I've had moderate success with my latest API product pointing to a "Boss Page" that outlines things like build-vs-buy costs, and why you really would be better off paying us for this thing rather than dedicating an in-house guy to building and maintaining it.
It's a tough one.