As of late 2023/early 2024, you can still purchase many recent 100 Taka commemorative sheets from the Bangladesh Post Office at face value. The secondary market value (on sites like eBay or stamp auctions) is where you will find the premium pricing for older, sold-out issues.
The standard postal rate for a domestic letter in Bangladesh is roughly 10 to 20 Taka. Therefore, a 100 Taka stamp represents . 100 taka stamp