This post may read like an advertisement, but I assure you it's not. I have no affiliation with the owners/organizers of PucaTrade outside of being a user.
I'm registered as Pineapple on PucaTrade, and I'd love to trade with you. The site's trading engine is based on a point system. Every card has a point value tied to the median price on magiccards.info.
When you send out a card on someone's want list you earn the points for that card. Once you've built up enough points in your own account for the cards you want, people can send them to you. It's an elegant system, and it's actually quite fun to send cards all over the world.
When I originally joined I assumed people would want to send lots of commons and junk rares and expect to receive chase rares, but the participation and good faith has been incredible. People have sent not only the commons and uncommons that people need to build their casual decks, but even things like fetchlands, Snapcaster Mages and Revised Duals.
My favorite card that I've received so far is Sylvan Library. The fact that it was a 4th Edition version has sentimental value to me, and Sylvan Library is one of those cards that I always liked and somehow just never acquired.
My favorite card that I've sent is Niv-Mizzet. I mean, how can you not like Niv-Mizzet?