I found them out from my parents originally, who wanted me to use a resume service.
I decided to give them a shot seeing how writing has never been my forte - I am in marketing so I'm not someone who's writing papers or long-winded articles very often.
I ended up working with a writer with a bit different background than me (he was in management), but marketing isn't a particularly technical field so I was okay with it.
I ordered on Monday and received my draft next week on Wednesday (so like 10ish days).
Though the draft had a couple of things that I sort of forgot to mention to my writer, it looked very well constructed and I was generally happy.
I thought it took longer than necessary to make the changes I requested (it should really only take an additional day, but it ended up taking 3)... but all in all, I can't complain because the end result was really promising and I have gotten a resume that is better than what I can do myself.
While it doesn't matter too much and may vary from writer to writer, I do think the writer I got was very kind and receptive to what I had to say.