Well, if you're able to source a 16x8 +30-40 or something, you could run the spacers. I trust the bolt on ones more, because those actually fit properly (especially model specific ones), and, someone correct me if I'm wrong, they distribute the load better rather than universal "slip-on" spacers.
If you're adamant on not using spacers, then look around for 16x8 +20.. Google, Ebay, Craigslist.. someone out there has them. I personally think without a good amount of fender work, and willingness to do it, 16x8 +10 might be out of your range.. unless of course, you're down to put in the work to make them fit.
Out of curiousity's sake, what wheels were you looking at?