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starbound is already worth more than double what ultimate ninja storm 3 is worth, so this is essentially a 1:4 trade
Steam store prices are almost always irrelevant. With the advent of bundle sites and 3rd party sites and sales. You can find games cheaper almost always outside of steam and most of the times for a lot cheaper.
Naruto is cheap since it was bundled recently and there are dozens of traders with copies in this site alone for less.
Starmade was bundled over 16 months ago. Its value has risen since then past Naruto's.
Google Enhanced Steam Plugin. It will help you tons with figuring out prices based on when the game was on sale , for how much , in what bundle , etc.
NARUTO SHIPPUDEN: Ultimate Ninja STORM 3 Full Burst (key)
2 copies of Starbound
1:2 trade
Or very good offer.