I rarely printed color with my inkjet either. Problem was, it wouldn't print black unless there was color ink -- the whole printer would stop. And it burned through color ink every time I powered it on, doing a cleaning cycle. If I never shut it off, the heads would stay exposed, dry, and clog. The lesson I learned was that I'll never, ever again buy an Epson.
My recommendation would be to abandon the idea of color printing at home entirely, and enjoy the incredible
cost savings of using a laser printer. You only print 500 pages a year, so what's the savings? Toner never dries out.
It's already dry. It'll keep until you use it. It's great! So if you still print just a few pages a day, you'll save by not burning through ink cartridges for nothing. If you do a job that requires a bunch of printing, a laser is dirt cheap to feed. You win either way.
My recommendation would be something like one of these, since you want duplexing:
(There may be better prices elsewhere; this just was an easy link.) I still have my old Canon scanner that hasn't died, so don't yet use an all-in-one. Currently I use a Brother HL-2170W B&W laser. Been going strong for years now; I'd buy another one in a heartbeat if I had to do it all over again.
For the one job a year you need color, just go print it at Kinko's.