Official Goldback.com exchange rate for 10/10/2023 is $3.99, up 1 cent.
Best prices:
1 GB is 3.64 (check, also free SD GB with purchase of SD) http://defythegrid.com/goldbacks/ref/6499/
1 GB is 3.67 (credit card)
https://finestknown.com/goldbacks-for-sale/
50GB is 181.13 at APMEX