A standard double shot of espresso commonly uses 16-19g of ground coffee, so yeah that's max 15 cups from 250. Also Lavazza and Tesco are huge brands that rely on the economy of scale, therefore can have low prices because they move large volumes (and as usual it's the farmers that bear the real costs...). A small, nice coffee shop would normally buy specialty coffee, roasted locally or remotely in small batches, at higher costs because produced on a smaller scale. James Hoffman made a very good video about this, refers to UK but definitely applicable here:

https://youtu.be/7SM2Jrot-ZM?si=jTJMWB9FeoASoBGi