Hey name is arcane vanguard Helmet it's for faster run/walk.
If you're referring to that helmet, it hasn't been farmable for a very long time. I would suggest going to the Warframe Market and checking how much Platinum it costs. You can then exchange that Platinum 1:1 for Gold. For example, 20 Gold = 20 Platinum. This way, you can determine the value of your items yourself. However, I believe that this helmet is very valuable and will be very difficult to obtain. So, if you happen to have one to sell, you can definitely ask for a good price. I hope this helps.