I honestly dont know, its your stuff, you know more about it than I do(I can only go from the pictures yours/ebay ect). My best answer for you, would be to look on ebay & craigslist for similar items, see what they are selling for (new/used) See how much they want for shipping. Look for tank prices, mask prices, other gear you have, and compare everything. How badly do you want to sell your gear will also have a impact on your sell price, if you want to dump it vs... I kinda want a decent return price. I think 300 is within the ballpark of what you may have paid for it new, it would be nice to get that, but improbable. Once you get a rough guess for your gear, toss it on craigslist, or ask around at a local field, I think that would be your best option.