I did a quick poke around for OEM flame rods too. The prices were a bit high but not horrible - they do ding you pretty decent for shipping though, darn near the same price as the flame rod...
Also, sometimes you can get an aftermarket flame rod from Universal Parts that will work too.
At any rate, do replace it Nub, it's too cheap not to do... I've been out of the service game for 10 years or so now. But I do recall "no heat" calls where I cleaned the flame rod and got her going again, only for it to fail again... Sometimes the porcelain insulator has a hair line crack that can give you intermittent problems also. If you have to sand it to get it going in a pinch, absolutely the right thing to do, but have a new one on top of your furnace because there is a reasonable change of it giving you grief again.
I was able to repair my electric dryer using http://www.repairclinic.com/
they have parts and instruction videos that were very nice
I got some parts from them, and some from Amazon that were same exact part, but better pricing
just throwing that into the mix
I will say my brother in law's boiler circ. pump went out. He found it on-line for $180, I got it through my wholesaler for $92.
Most manufacture's work through a wholesaler. Try buying a Carrier Furnace from a wholesale anywhere else than Auer Steel in Milwaukee. Let me know the best price you find on-line SFBSG, I can assure that a "Carrier Dealer" can buy it for considerably less. The mark up is up to each dealer.
If someone is selling an OEM part, they are making a buck off of it. If they have an OEM part, they purchased it from the manufacturer.
For Nubby, I'll pass it on for cost, just for being a fellow Linker.
Also, JJ I didn't say "always" but many times after a flame sensor starts giving you grief it is short for the world. They have a protective coating on them that lasts for years. Once you "sand" it off, many times they fail within a year. Not a guaranty as some of them will last for a while, but many of them won't.
I pull and clean my flame sensor every year. Several years back woke up cold in the morning and could here the igniter clicking away on the furnace. Check and the pilot was establish, sensor just didn't know it. Cleaned and good as new
I'll have to get it from one of my wholesalers i.e. Larson, Auer Steel, Design Air, etc... They are usually not available to the general public.
Long story short AC current is applied to the flame rod, and if all is working well is rectified into DC current. So long as there is DC current, the flame module knows that life is good, flame is present, and the gas valve can open and ignite the gas. If DC current is not present it closes the gas valve so that your furnace doesn't fill your house with natural gas and explode when your water heater or gas stove ignites.
At any rate, my experience is after you clean them, order a new one, because it is likely to fail again, and cleaning it with emery cloth doesn't always work. Also, Murphy's law is that when it fails again it will be midnight on Christmas with an outdoor temp of -20.