[raulus]

Usually your best bet to pick up the commons is going to be on eBay or else through a dealer.

There are a number of dealer-type sellers on eBay who are breaking up larger sets and who offer the option of picking the card that you want from the set. Obviously your one card isn't always going to be on the list, but scrolling through those should be part of your strategy.

Sadly, any way you do it will probably both require a lot of patience, and you may have to overpay a bit to get what you want.

Otherwise, about your only option is usually to buy a larger lot that happens to include the piece that you really want. And then spend a lot of time trying to offload the pieces that you didn't really want but had to buy to get the piece that you really wanted.