But did you count the factor of a BB card? (since you brought a propriety card into discussion)
Not advertising for BB though, because I do agree this GC offer is negligible. Seen much better deals.
If you open a BBY Credit Card, you get 10% back in rewards on your first purchase; otherwise it's 5% back for existing non-elite members, and 6% if you're elite.
So going off
@bbeagle's post for consistency:
New BBY credit card: $949.99 + tax = $1033.11 at Best Buy + $50 gift card + $103.31 best buy rewards = $1033.11 OOP + $153.31 to spend at Best Buy.
Existing BBY credit card (non-elite): $949.99 + tax = $1033.11 at Best Buy + $50 gift card + $51.66 best buy rewards = $1033.11 OOP + $101.66 to spend at Best Buy.
IMO, you can't subtract the value of gift card and rewards since it doesn't minimize the amount you paid OOP. If this is the sole purchase you're making, Target might make more sense. If you plan on following up with accessories but can wait until rewards post, etc. I think having an existing BBY credit card makes sense. At only $103.31 in best buy rewards for opening a new credit card,
it's not worth the credit hit. Since you can get better card deals and a higher cashback bonus from other card companies.
EDIT: To clarify on the accessories part - at Target you would spend $981.46 OTD; which is only $51.65 less than Bestbuy. So let's say you want to buy an Apple Pencil at $100; 5% Redcard drops it to $95 + tax.
You're already paying more OOP than BBY. Ideally, you would find the cheapest place for accessories (*cough* ebay *cough*), but this is just taking into account retail prices at retailers.
EDIT 2: We can also sell the BBY for say $45 ($40 + $5 in value for our time in listing, shipping, etc.). That would bring our OOP total at Best Buy to $993.11ish, which lessens the gap between the two to $16.65; but we still come out on top at Best Buy with $51.66 in rewards (existing card holders); $103.31 (new card holders).