I can assure you that a ton of scripters make a lot more from botting than from selling scripts. Other scripters make more by selling scripts because they suck at botting.
Botting isn't just following a set of rules to have success, else we'd all be swimming in mad cash. You're right about the latter though, ban rates are insanely high right now and that's due to prime season.
I don't know where you get this info from, but I can tell you you're wrong. I've had hundreds, if not thousands, of bans on my home IP but I keep going. Meanwhile I'm also playing my main which doesn't get banned. It isn't purely IP based. A lot of people have indeed given up on botting, because nobody succeeds at first. It's the ones that persist and learn from the past that actually make money botting.
$100 for a private script, no matter what it is, is peanuts. Heck even a GE Ash Collector would probably cost you that much. You're not paying per line of code, you're paying for the time they spend on you and their past expertise. Since he delivered the script after an hour, it appears to be rushed to you. On the other hand, what took Gastro an hour, might take a beginner scripter several.
Like others have said above, it seems like you didn't specify enough. This is the main issue when a client isn't happy with what they got.
I'm not sure what image you have of scripters, but you seem to think they're from a poor country and this is their main source of income.
Every scripter I've met so far, has a job, family and duties besides dreambot. Scripting is a hobby, we do it for fun. Getting something more out of it is just an extra. (that's my view at least)