I owned a similar domain name, BuyAutos.tv and was unable to unload the darn thing for the longest time and just let it drop. It's one of those situations in which you have the correct keywords but the extension does not necessarily fit the content.
SellGold.tv is hard to consider from an end user perspective. Would those who wish to sell gold upload it to a website that uses video to display it? Sounds kind of awkward. Now GoldTrends.tv, GoldSpot.tv, BuyGold.tv, InvestGold.tv etc. might make a bit more sense but again, it's a tough one. I am NOT recommending you buy or register any of these.
The other thing to consider is the competition you are going to receive for these keywords. Anything like this that is so hot is going to be incredibly tough to get a foot in and compete with other domains of similar nature.
My advice is that these types of domains do best on an eBay no reserve auction. You might be able to recuperate your original investment, but that may be difficult. My appraisal is a reg fee.