I bought a microUSB OTG adapter for my phone from starangle88, a Chinese seller on eBay, for only $1.00! Shipping was free and it took 11 days to arrive, which is pretty quick compared to other Chinese sellers. The quality of the plastic feels a little cheap, but still good enough to last many uses.
I tested this OTG adapter by plugging in my USB extension cable, which connects to my USB hub, which has my Apple keyboard, Logitech G9x mouse, and HP printer. The keyboard and mouse worked great, just as expected. However, I was unable to use the printer to print anything. It could be that my printer is too old, or I didn’t have the right app to make it work, but I don’t mind because I wouldn’t be printing anything from my phone anyway.

