We (LHS) split sets frequently...especially after the holidays. We typically can make money doing so because the MSRP's for components totals much more than the MSRP of the set. This is not just a Lionel 'thing'...all model train set producers have prices that deeply discount the individual prices. It's called 'incentive'...that first step, which sets often represent, into the hobby. Because it's advantageous, we can then discount the prices of the individual items. Even if we break even on the original pricing of a set, the customer(s) win! Such a deal!
That said, we do not have a Peanuts set. Can't help you there. But the advice to buy a set to get one special item is fairly sound...as long as you are willing and patient enough to market the other items.
KD