cruisercruiser,
It cost me close to 22K Ringgit to get my PPL in EFC, that's inclusive of all the exams fee, books and equipments. But that's in 2005-2006.
About continuity problem, it depends... some people managed to maintain their flying standards even though they only fly once a week, but some people struggle..
However as my ex-instructor put it: "Flying is 10% skill and 90% attitude", so if you put a good attitude towards learning how to fly, you shouldn't encounter any major problem.
JA