-the past participle of pello is pulsus. Thus, you have a form of sum in the imperfect (erant) with a form of the past participle (pulsi). Which tense is this?
“pulsi erant” is indicative pluperfect pasive.
-novem is a bit tricky. You read it as a form of novus, -a, -um - but “em” is not a valid ending in 1st/2nd declension adjectives. Novem is actually an undeclinable numerical adjective meaning “nine.”
-Gerebat means “was carrying” or “was bearing,” though “had” is a rough approximation.
-When certain short words depend on cum, it becomes an enclitic (like -ne, -que, and -ve). For instance, mecum, tecum, secum, quibuscum. These all mean the same as if cum had preceded the pronoun (cum me, etc, which is very uncommon if not impossible). Hence, secum means “with her.”
-Note that “nine books” is the object of “was bearing.” Your translation doesn’t specify this.
Yes, you are right, my mistake.
So, right translation would be:
Same Sibylla was bearing nine books, which she wanted to sell to king.
eidem is the dative singular, not the nominative plural. So it must mean: ‘to him, books are worth nothing’ or ‘to him books are priceless’, depending on how you interpret the idiom.
Eidem can be both dative singular and nominative plural. Nominative plural is for m. iidem, idem, eidem.
This sentence is out of context which I will give now:
Eidem libri, si empti et diligenter servati erunt, utilissimi et tibi ipsi et civibus tuis erunt. Eidem libri pretium non habent.
So Eidem can mean here I think both “to him” or “same”.
“pretium non habent” it this context I believe it mean “priceless”.