I don't think it is a particularly rare game and plenty of official emulated versions are also available. I will confess though I don't know what the reference version of this game is for many people -- there was an arcade version after all but being Atari I don't know right now if I am looking at a decent port or an atari pac man a like.
Most pre NES games, with the possible exception of the SG1000, don't command a great price, and Ebay is seldom a great guide for things.
To that end you are probably going to have to sound out the market yourself, or set a reserve price you think you can live with vs having it on your shelf of cool things (or playing it if you are so inclined). If it is something like collector grade that might pump it up a bit but I don't know how that works for the Atari, and if it is anything like the NES collectors with all their weird quirks then I would not want to speculate. What time will do to the price I don't know -- I don't think we are going to see a resurgence in the Atari aesthetic and it was never amazingly iconic compared to the eras we know as the 8 bit and 16 bit eras.