I might point out that starting to learn escapology by 'starting with handcuffs' is rather like wanting to begin in magic by 'starting with stage illusions.'
Escapes from handcuffs, particularly if you are thinking in terms of learning enough to accept or stage an occasional challenge, is a very specialized facet of escapology requiring a lot of study and expense. While purchasing ONE handcuff (legit or gaffed) is one thing, 'learning handcuffs' is a different matter entirely. As the late Prynce Wheeler pointed out, to be a handcuff king, you first have to become a HANDCUFF COLLECTOR, so you will know what you are working with.
My suggestion is to get a few good, all-around books on escapes (Cannon's Great Escapes sells several, including the 'Encyclopedia of Escapes') to get a good 'survey' education on escapes.
Learn some basic principles (rope ties, chain releases, boxes, bags, etc.) Learn how to PRESENT escapes (learn from other escape performers, or try to find a copy of Burling Hull's "Gold Medal Showmanship,' which has a chapter on Showmanship for the Escape Artist; Abbott's Magic Co. might still carry it).
Beyond doing a simple escape with ONE handcuff, truly LEARNING handcuffs will require you to begin the expensive (but fascinating) hobby of COLLECTING handcuffs.
To get you started: