@Vivid I made a
calculator spreadsheet precisely to help people figure out the best way to approach buying a CYS enabled set.
If you would still like to try to understand the working of CYS then...
1. For your first question I'll just quote a bit from the first page of this thread:
Shogo_Yahagi's No-Math Guide to CYS
If a set allows CYS credit:
1) If you don't own anything from the set, always buy the cheapest item in the set before buying the set, even if you have to pay full price.
2) Never buy an item with less than a 10% discount, unless it is the first item you buy.
3) Always buy an item with more than a 10% discount, even if the set is going to go on sale later for a better discount.
As long as you know those three rules, you can always save SP, even if you have no idea about the math under the hood that makes them work.
2. The CYS calculation always uses the full price of an item, regardless of what you paid for it or if it is on sale. So the Book of Spells will always count for 395 SP and the Magic Cauldron will count for 461 SP. These two PC items contribute a combined 856 SP towards Enchanted Bundle's CYS, making the set's appearance on DD #19 free!
Once you own Enchanted Bundle you should check out More Magic! on
any of its DD appearances to finish that set for free as well, then January 2012 should be acceptably cheap too.
