Its not a money thing at all.....
Lake owners want you to catch....FACT , so they will recommend bait that works on their lake you can choose whether you buy that bait in the UK or actually at the lake & I am sure that the price wont vary greatly.
Lake owners buy bait at trade prices, the same as tackle shops, and will sell them at rrp or maybe less, but we have the logistical problem of getting them back to the UK within 24 hours to freeze.
SOME holiday companies have ties with bait companies & will recommend their bait for ALL their venues, although it is highly unlikely to be successful on each & every one of them.
I would always advise you to check with the lake directly and get their advice then it is your choice where you buy it from.