One of the better features in FONV was the return of implants. However, they could have gone further with it. The V.A.T.S. could have been explained by an implant, or even some of the perks. What are your thoughts?

Idunno about additional implants but I think that for simply buying them the price should be way higher. (Trice what it is now)
And for there to be implants to find around the world, if we find one and bring them to those who can install them we pay only around 30% of what they should cost.
That way we get to choose whether to hunt them around or pay ridiculous sums of money for them.

I think Implants should stay as they are, lest the they become too much of a focus - that belongs to CyberPunk games like Deus Ex.

What if they could be the reward of a quest? I just think that implants should be precious things not to be distributed by some vendor, and the price to install them should be very high (like the number Gabe suggested).

A handful of quests (3 at most) could yield implants as rewards, though the quests has to be damn hard quests too, and only if done perfectly are you awarded the implant.
For those that you can find you need to go through some of the most dangerous dungeons in the game.

However it's done they should not be available at the get-go to anyone with a 10K+ caps.
People should really have to work towards them. (Which is why I don't like getting implants in Vegas, far too easy.)