Seriously?  If someone walked up to you on the street and said to you "I have a $100 bill I can sell to you for $20" would you ask that same question?  What do you think the other person would answer?  "Nahhh, they are counterfeit."

That being said, the way to resolve your concern is to ADD it to your account as a separate card rather than add it to your existing card.  If you pay with your phone app you just select the card you want to use. Rotate between the cards. They won't close your whole account just the individual card. (I have 6 cards on my account right now).  DO NOT merge/top off them with your LEGIT card (legit=the one you paid full price for).

   If you REALLY think any, not just from this guy, of these cards are legit you have to be hallucinating. Do you think Starbucks is selling all these sellers $100 worth of product for $10 so they can sell them and make $10 each?   I've bought a bunch of them ($800+) over the last few months (NONE FROM THIS SELLER) and have had only one problem.  Spend the first $20 on each card real quick and anything after that consider it a win.  If the cards are still good after 2-3 MONTHS then you should be safe merging them with your regular card but I still wouldn't do that.  

Are they legit?  Yea, sure, wanna buy a bridge in Brooklyn NY?   Do they work?  For the most part I've been quite lucky. YMMV

I'm interested in topping off my starbucks card but not interested in having a card get cancelled on me.  Are these puppies legit?  Are you guaranteeing they won't be shutdown unexpectedly?

just paid.  i forgot the damn paypal is my wife's...LoL.  i wanted to buy 2 cards.  can you send me another request for a 2nd one ?  thanks.  i am going to PM you.

Quangvuvn,  i'd like to buy one of your cards.  can you PM me and give me the info.  thanks

Good luck with your shop...my email,

Antminersales@hotmail.com

PM sent, i want to buy 1.  thanks

I'll be damned....i received it in the email.  i will go try it.  i am leaving you positive feedback. 
will be buying from you real soon.  Thank you

I would like to try.  Thank you
itguy1700@gmail.com

I'd love one of those $5 cards to try it out. My email is lucasmaynardschooll@yahoo.com

Thanks!

+ I  am available 10 starbucks gift card $ 105. If you wish to use them please contact me.
Price : $30 for one or $28 for more .
+ Accepting Paypal today ....

Nice shop and good luck!
Snta527@gmail.com

11 >lorrie.ferrante@gmail.com
12 > sellinghbogo@gmail.com

Did not get any email!  kashish948@gmail.com

Cause that's how scammers work...

1 > idipchips@gmail.com
2 > ftoole11@gmail.com
3 > milkcookiebtc@gmail.com
4 > kashish948@gmail.com
5 > i.m_me@live.com
6 > ptcc0in@gmail.com
7 > asteroorder@mail.com
8 > arreyabond@hotmail.com
9 > peter.b.k.1111@gmail.com
10 > 1998ric@gmail.com

do you have physical cards? are these legally bought?

LMAO!  Price wars! I guess the stolen credit card market is booming! 

You are buying

GUARANTEED US$100 STARBUCKS E-GIFT CARD!

-Fast delivery 15 – 30m
- 100% safe!
- Redeemable in-store or online
- Add this card in your Starbucks account,and use it with your Starbucks APP on your smartphone.

No hassle, easy and safe!!!

All orders will be 100% guaranteed from me. And will refund 100% if there is any allegation of dispatching you. During 14 days from the time you receive the gift card

You go first, or you pay the escrow fees, and then I will PM you the card # and card code or I send an egift to your email address which you can print out OR import into your account.
Thanks you !!

You go first, or you pay the escrow fees, and then I will PM you the card # and card code or I send an egift to your email address which you can print out OR import into your account.
I will sent you request money from money to email paypal account you give me . After i getting money . I willing sent egift direct to email paypal for you . Please remember it's only sent gift to email you recevied requesr money and paid money to me . Thanks you !!

Update end day !!!
Thanks you !!