Best Buy Deal from CashStar is back:
https://bestbuy.cashstar.com/gift-card/buy/
https://bestbuy-m.cashstar.com/buy/
Buy $150 in Best Buy e-Gift Cards, Get a $15 Savings Code (or buy one $450 e-Gift Card for three $15 Savings Codes)
- Valid 2/18/18 – 3/3/18 online only.
- $15 savings code will be provided via e-mail on 3/18/18 for use toward a future purchase made from 3/18/18 – 3/31/18.
- Maximum of 3 $150 e-gift card purchases during promotion time period per customer and savings codes will be sent via e-mail in $15 increments.
- Valid e-mail address required to receive savings code.
- Savings code may be redeemed online and in store.
- The value of the savings code will not be refunded if merchandise is returned or an order is cancelled.
ETA: Most recent data points say you can still use Best Buy gift cards, savings codes, and reward certificates in store to purchase third-party gift cards like Disney. A cashier at my local store told me that policy would be changing in February, but so far no changes (or any word of changes when asked) from all your reporting.
Your best bet is to redeem these in store. Best Buy's in store POS system accepts its gift cards as a form of payment for third-party gift cards like Disney, but not open loop gift cards like Visa prepaid gift cards. Some stores, cashiers or managers may give you trouble and claim it's not allowed at all (even though it's fine for Disney) so YMMV.
A lot people have problems using Best Buy gift cards to order third-party gift cards online, as those orders tend to get cancelled automatically because the site will say it can't verify your information for whatever reason.
Most Best Buy stores sell Disney gift cards in fixed $25 and $50 denominations and a variable load card that you can put any amount on from $25-500. Remember to use either Shopkick or Ibotta when you check out for additional points back towards more free gift cards.
Promotional savings codes look and act just like gift cards, but promo codes expire and gift cards don't. So be aware of the expiration date since it looks like the promo code will arrive via email about 2 weeks after the promotion ends.
If you have a Chase Ink Business Preferred credit card ("CIP"), use it to earn 3x UR points because these gift cards are processed through CashStar, which seems to code as internet services or utilities. Chase Ink+ and Ink Cash credit cards should earn 5x UR, but I don't have any personal data points.
One more thing, when buying the Best Buy e-Gift cards through CashStar, there should be a field where you can enter your My Best Buy membership number and earn points towards reward certificates. If you’re a regular member, you get 0.5 point/$1 spent and 250 points gets you $5 reward certificate (or 1% reward); Elite members get 1 point/$1 spent (2% reward); Elite Plus members earn 1.25 points/$1 spent (2.5% reward). Reward certificates can be redeemed towards Disney Gift Cards (or almost any other item or third-party gift card Best Buy sells except for prepaid gift cards).