Here are charts showing the relative values of gifts, and therefore how much you should pay if you are looking to buy. Despite Rank 5 Pink gifts being slightly overpriced you should still consider them simply because of the time savings involved.
Influence Gain at Influence 40+ (without Legacy Perks)
We based our numbers on the excellent Dulfy article on version 5.0 Companion Influence in SWTOR.
Legacy Perks, which can increase Influence Gains by up to 30%, will influence these numbers somewhat but not by much.
Influence Gain Relative to Rank 5 Blue Gifts
Relative Value of Gifts
Vendors exist for the following:
- Rank 1 Green - 200 credits
- Rank 2 Green - 600 credits
- Rank 5 Blue - 5,000 credits
- Rank 5 Pink - 10,000 credits
- Rank 6 Yellow - 250,000 credits
Other Influence Ranks
At different Influence Ranks, different Gifts are more cost-efficient (though definitely not time-efficient in terms of actually giving the gifts):
Short of someone dumping gifts cheaply on the Galactic Trade Network, the cheapest way to get gifts is generally Crew Skill Missions which can get you a Rank 5 Blue gift for under 2000 credits, and a Rank 5 Pink gift if the follower has a critical success.