A lot of eBay items are like that. My favorite reply. "Set of four new Michelin tires, all sizes $49.95 each complete. $1,395.00 shipping. I have gotten some pretty saucy replies, usually by women."
But some folks charge ridiculous prices like the above. Absurd shipping at 150% of the going eBay price. I forward the ad to the California state resale board --- obviously cheating on state tax. The ad disappears after a few weeks.
I just had it out with an eBay seller. Weatherpack sets with gray silicone plugs which matches the picture in the ad. Red silicone plugs are half the cost and red is what I received. Cannot force it over an 18 gauge wire to save your ass. I 1-starred the vendor and issued a public warning. He wanted to send me a check. I told him it would cost more in gasoline than the five dollar check was worth. He ended up crediting my Visa account $7.50 I sent nothing back.
On O Rings. WW Grainger sells a huge variety of o-rings. Worth a visit. Probably will find far better product at one quarter the price.
Beware of counterfeit junk.