Just get started, once you get over the hump of sending those first few out you'll be hooked again!

I would say go for it. A lot of athletes and celebs themselves don't like the idea of their autograph being sold on ebay when acquired through the mail because they seem like something you acquired "free" but keep in mind you took the time and effort to acquire that. If someone is interest...

Not a TTM site but I own a retail company: http://www.3monkeysports.com. Check us out!