Send 'em out. Costco, Walgreens, Sam's Club, Wal-Mart. Even some of the on-line options are good. As long as they are in sRGB and you've had a few test prints made, you should be fine.
You may be able to get the paper/ink cost to .25c for a 4x6 printer, but that doesn't include the amortized cost of the printer itself, all the bad prints you throw away, or any of the many, many hours you will spend doing this. My local Costco is .19c per print, and my local "pro" lab is .24c for bulk orders. And I don't have to stand there while they print them.
We're in the process of organizing 20 years or so of family photos, and I have a folder with over 800 4x6 files. You bet they're going out for printing.
--Ken