For me, this was a particularly big year for bike purchases, as I spent nearly $50 on my ride!
As I've discussed in other threads, in 2013, I bought a $25 Schwinn rack trunk (after buying and returning several panniers costing up to ten times as much), a $20 Mirrycle mirror (best purchase ever), and...oh yes, a $5 thirty-two LED flashlight for my handlebars that projects more light than any other bike light I have ever owned.
The jury is still out on the rack trunk, as I haven't used its pannier fold-outs for a real "tour" yet, but as a commuting accessory, it was a great choice. I'm also waiting for the $5 flashlight to burn out or explode (the way numerous critics on these forums advised it would by now), but so far, it's working just fine. As noted, I can't believe I waited so many years to get myself a real bike mirror. This thing has completely changed the way I ride and the way I perceive the road.