Originally Posted by
RustBeltRaw
I use a Canon RC-6 infrared remote for slow-shutter and bulb shots with a monopod or tripod. For bulb shots, you have to hold the transmitter's button for the whole duration of the shot. Not bad for anything up to about 1 minute, but something of a pain for really long exposures. For short-range work when you really want to avoid touching the camera, it's great, but I'm normally using it at a range of about 6in (~15cm).
To put some number's on Manfred's qualitative information, I have a trio of Pocket Wizard FlexTTL5 radios (finnicky, but useful), which can be used as remote triggers, and are one of the longest-range solutions. They list at $220 apiece (eBay got me well under that), and you need 2 (receiver and transmitter) to trigger a camera. The cable to connect the receiver to the camera costs more than Canon's RC-6 IR trigger. Fortunately, there are middle-of-the-road options like the Vello FreeWave radio trigger ($60 for a 100m range, bulb-compatible transmitter and receiver) at the top of the page Carl linked.