There's a whole 10,000-yen difference between the weekday and weekend rates.
Literal
Weekday rate [and-と] holiday rate [with-で], 10000 yen [even-も] different.
平日料金と休日料金 pairs the two rate types. で here means 'with/at' — marking the frame of comparison. も after 1万円 emphasizes that the gap is surprisingly large: 'as much as 10,000 yen!' んだ at the end is explanatory — the speaker is expressing surprise or frustration.