About a month ago I asked about getting Kindle books with my PBS credits (instead of paper books because I have allergies),

and someone suggested selling my credits in exchange for Amazon gift cards (which I can use to buy more ebooks). 

Could you give more detail on how I do that?  I'm assuming that I transfer my credits to another member, and that

person purchases the gift cards and somehow  "gifts" them to me?  ...and what is a reasonable amount to charge per credit?

This happens over in the Book Bazaar.  I recommend you check out what the going prices are over there.

As Emily suggests, you have to check out the going rate. Your credits wont sell if they're too high for the going market.

I've sold credits for Amazon gift card, and bought them that way. You just agree to a price with someone in a PM. You'll need to give them your email address. They buy the gift card and have it sent in email to your email.

You'll get an email from Amazon saying someone's giving you a gift card. Copy the code supplied in the email to your Amazon account. [Go to "My Account" and then click on "Apply a Gift Card to Your Account".] Enter the code and "Appy it to your account".

It should say on the right how much you just deposited. At this point, you've been paid and can then immediately 'Gift" your credits to the other member.

Once we start PMing each other the agreement and the email address, usually takes less than 30 mintues to get the whole transaction done as long as I have access to keep checking my email. I've always sent payment first, then got the credits, or when selling waited until I was paid to gift them over. I've had no problems with that. Just make sure you let the other person know you expect payment first.

IIRC, you can only "Gift" up to 50 credits a month. Except for games, maybe. I'm not sure about the games gifting. But you won't be able to sell more than tha a month.

doesn't look like it's an issue here, but just for reference.  :)  if you play games, giving a credit to a game host does count against your 50 for the month.  (and it does tell you that when you send it to them.)  if you're a game host and you send to a games moderator, it does not count against your monthly total.

the couple of times i've sold credit i also got payment first.

You can also earn Amazon GC's at Swagbucks.  I don't spend very much time on Swagbucks, but I get a $5 Amazon card every three weeks or so.  450 points will get you a $5 GC.  It's a pretty good bargain.  

Does your library have e-book downloads on loan?  Mine does, and I really enjoy it.