With a few mods, here's a $25 wireless mic that you could use for your DSLR!
The Fifine K037 is a digitally controlled 20-channel UHF wireless lapel system. It was originally designed to work with audio systems where you could plug it into an audio mixer. Apparently, it uses a 1/4" audio jack, making in incompatible with most DSLRs out of the box. Audio adapters may be available online, but using one would only give you a mono output. This mod will teach you how to add an Female audio jack to this wireless mic having a combined mono to get a Mono-Stereo output.
Discounted Product Link: https://goo.gl/UwKF3R