Being a good trader (Advice Needed)

It's on the 15$ tier, you can get 3-4 keys for it. Also it'll gain more value with the time, a bundle game gets more and more valuable after the bundle is expired. But never ask for the direct Steam Store price, nobody uses that.

1. Steam platform > Uplay/Origin (Crew on Steam will fetch a higher price than Uplay/Origin).

2. Some traders will set a key price corresponding to monetary price. They usually can't sell since people can get the same game cheaper somewhere else.

3. DON'T sell it for 1k, that is not a fair price for it imo. I believe it was in Tier 3 ($15).

Awesome, thank you everyone for your advice :)

If you are curious about the market value of a key, you can always check the grey market, namely G2A. Currently that key is listed for almost 9 USD. Try to undercut it some, and you can have a reasonable chance to sell the key without being skimmed. So as it was said above, you can ask for about 3 CS:GO keys for that Uplay code.
Keep in mind though that Uplay codes are usually less valuable. So are Origin and GOG, but in those cases it is not that of a solid rule – sometimes Origin has exclusives, so keys are expensive, and with a few games, people prefer GOG's DRM-free format, driving up the prices.