Like one of the above posters said, the best way to show your support is to buy the coins and spend them. Luckily, the US Mint is selling them - $250 at a time - on your credit card.
Some enterprising people have used their 2% cash return credit cards and are just ordering boxes of them and wheeling them direct to the bank, thousands of them at a time, which defeats the whole purpose of the program. But, if your transit agency doesn't accept credit cards, you can get these "tokens" at a 1-2% discount, depending on what credit card you have.
Place your orders here. (And no, I don't get a percentage. You'll notice I don't even have a tip jar.)