I mean that, when a noun like "prices" functions as a noun, not as an adjective, the "-s" should not be dropped (see the last sentence below):
- I am creating a price list. OK (here "price" modifies the noun "list," so it is adjectival and does not take an "-s")
- ... for different services types ... NOT OK (similarly to the sentence above, you should say "service types")
- ... and the corresponding price. NOT OK (you should say "and the corresponding prices," because the different services you render have different prices. Here "prices" has plural meaning and functions as a noun, so there is no reason to drop the "-s.")