I thought I'd update you on where I am so far ...
I uploaded Penance a month ago. The uploading itself was relatively easy (at Smashwords) but the 'approval' from Smashwords took a while (a few days). Amazon was much, much faster. Note that the person who formats for me does a fabulous job of vetting the finished product, so I'm assured it will look fine once uploaded and I'm assured it will pass Smashwords' verification process.
So far, just a few sales. BUT -- I haven't promoted it at all. I'm using this as an experiment to see what promotions might work and what don't, because I can track royalties immediately with my self-pubbed books. There's real-time royalty reporting there.
In a week or two I'll start purchasing some promotion space at review blogs, etc., and I'll track progress. Then I'll do the same at other review sites. I'm willing to take the time at this because I'm truly curious about what works, what doesn't.
Here's my costs so far: $120 for cover; $50 for formatting. I'll be tracking other expenses as well. I'll be happy if I make a profit, and if I don't, I figure it's still worth the try.
I'll keep you posted!