Usually when I look for an album, I'm looking to get a complete copy, i.e. with the obi, registration card, stickers, and any other original extras, all in really nice condition.
After collecting for a couple of years, I've found that for some albums, finding such a copy is extraordinarily difficult. This is particularly true for albums with multiple extras, e.g. Super Mario World, which has an obi, registration card, and 3-D jacket.
In the case of Super Mario World, I've decided to try getting a complete copy by buying several incomplete copies, and combining them together. After settling on this strategy, I saw a copy with the 3-D jacket only for 7500 yen on YJA, and decided to buy it. A few weeks later, I found a copy with both a 3-D jacket and an obi for $100 on eBay, and bought that as well. Eventually, I'm hoping a well-priced copy with a registration card will turn up - at which point I can buy it, combine the three copies to form one complete copy, and sell the remaining two copies + extras.
I thought I'd ask whether anyone else has adopted a similar strategy for any album, and if so, how it went. In the case of Super Mario World, thankfully it's a popular enough album that I don't expect to be caught "holding the bag", i.e. unable to sell the extra copies. Though for other albums, I could see that happening for sure.
I also realize this sounds more difficult than buying the extras separately, though finding a loose obi or a registration card is probably even harder than finding a complete copy in the first place. I also accept that some folks will find this all a little nuts...