It can be worth it...but! Until you master it, expect to toss ruined fabric into the garbage can <img src="/forums/images/graemlins/wink.gif" alt="" /> So your first couple projects may cost you a couple times more than buying premade <img src="/forums/images/graemlins/tongue.gif" alt="" />
Your best bet is start small: a couple stuff sacks from a pattern.Then go up to the big stuff. Learn how to sew all the types of fabric - be it silnylon, stretchy spandex, tough cordura, etc.
When it comes down to machines....I sewed on a $100 Singer for many, many years. Is my current Pfaff machine that much better? Not really. It is more fun to sew but for sheer hard working, that old Singer I bought new in 1992 or so worked like a field horse!

Just remember: use the right needles, keep your machine clean (use a dusting brush often) and life will be ok!