Upload & Sell: Off
The Canon system works by sending coded pre-flash messages to the slaves from a Master flash unit (580ex series / ST-E2 (ETTL only) controller). These commands occur rapidly between the time the shutter is fully pressed to take the shot and the main flash fires so you can't typically see them separately from the main flash.
The Canon 7D camera can also control slaves with its built-in flash but AFAIK the 60D can't. All the 60D can do is control a 580exII Master flash in the hot shoe from via the camera menu vs. using the user interface on the flash itself.
If you use a manual flash like a Vivitar 285HV in the hot shoe or connected to the PC socket you can trigger slaves optically with a Wien Peanut trigger. I shot that way for 30+ years...
The advantage of optical is that it's cheap. The Wein Peanut slave sensor is cleverly designed to fit directly into the base of a Vivitar flash, but that tends to limit it's ability to see the light from the flash connected to the camera which is triggering it. All things considered you are better off with a radio trigger system if you use manual flash. The older PW PlusII, Buff Cybersyncs, or any of the Chinese triggers will work.
While you think you can't afford a Canon flash you should stop and consider how much the alternative will cost you and where you'll be 2-3 years down the road. A lot of people buy cheap solutions initially wanting all the pieces at once only to find they outgrow them and abandon them, winding up wasting the cost of the initial investment. Having use both I don't regret investing in the Canon gear. This explains how I use it: http://photo.nova.org/CanonPracticalUsage/
If you are looking to do mainly fixed location studio work speedlights are a poor equipment choice because they lack modeling lights, recycle slow, and aren't designed for use with modifiers like softboxes. If studio work is your goal investing instead in a monolight like an AB400 or AB800 would be a more prudent long term investment you can build on.
If your interest is more in fun and gun PJ style edtioral shooting a good incremental strategy would be to start with one used Canon flash on a bracket (430ex/550ex/580ex) and learn to max out its capabilities (which are many) while saving for a second, winding up with a more versatile solution you can use Manually or in ETTL mode, with HSS capability outdoors to use wide apertures and blur distracting backgrounds.