question: masterpiece ratbat single item sale expectations?

So I'm new to collecting. Found a soundwave at toysrus with 5 cassettes at a great price.
saw ratbat and want it but as i said im new to this and have some questions.
I saw single cassette masterpieces are sold in packages of twos (ravage+laserbeak for ex.). ive seen some single cassette being sold on ebay too but am not sure if they are second hand or what.
basically when the time comes, what is the best way to get my hands on ratbat without having to buy soundblaser? and any other of the already existing cassettes too.
what would expectations be in relation to past releases of masterpieces?
is ebay the best solution to get 1 at the lowest price?
How much can i expect to pay?
when would it be better to buy (in ordwer to pay less) like; will the price only go up after release?
answers/insight to any of the above is appreciated
thx in advance.
saw ratbat and want it but as i said im new to this and have some questions.
I saw single cassette masterpieces are sold in packages of twos (ravage+laserbeak for ex.). ive seen some single cassette being sold on ebay too but am not sure if they are second hand or what.
basically when the time comes, what is the best way to get my hands on ratbat without having to buy soundblaser? and any other of the already existing cassettes too.
what would expectations be in relation to past releases of masterpieces?
is ebay the best solution to get 1 at the lowest price?
How much can i expect to pay?
when would it be better to buy (in ordwer to pay less) like; will the price only go up after release?
answers/insight to any of the above is appreciated
thx in advance.