Official Goldback.com exchange rate for 10/12/2023 remained $4.00.
Best prices:
1 GB is 3.65 (check, also free SD GB with purchase of SD) http://defythegrid.com/goldbacks/ref/6499/
1 GB is 3.70 (credit card)
https://finestknown.com/goldbacks-for-sale/
50GB is 181.81 at APMEX