How much are my cards worth/ what is the market value?
How much are my goddess story cards worth?
Long story short, there is no reference value for a specific card. The market for waifu cards is not big nor liquid enough to have values based on natural price discovery (equilibrium between supply and demand).
If you want to be treated fairly in terms of pricing, the best way is to look at what sellers on websites are charging for that card (many sellers sell singles but will involve a bit of searching). Also use common sense in terms of how rare/desirable a card is. E.g. a PTR card from an NS-2MXX set would be worth more than a PTR from an NS-5MXX set as PTRs are harder to pull in the NS-2MXX series. Also think about how often that rarity appears, and how much a box would cost etc.
For more information please check this video from @TCG Comrade at Youtube:
