why would I spend tons of money on something that I'm not going to be doing professionaly. I am a hobbyist, so I don't plan on putting that much money into my equipment. ...
I know some guys that have GREAT sets of golf clubs, and still hit over 90, but just love whacking the ball around and having fun. No aspiratins to go pro.
you're in the same boat. so there are reasons to want good stuff, even if it is a hobby. Would you do wood crafting with children toys and just a hammer and screw driver? No...you'd probably want a nice "shop" for your hobby.
However, get yourself a good set of headphones (groan..) like the Sony MD7506 and get used to them. Or, if you want some ear buds, get the Sony E6 in ear monitors... BOTH NOT used or aimed for playback, but will be your best $100 spent. I'll probably take some flack for suggesting headphones, but for $100, you'll like them.
What people are saying is that if you play your music somewhere else besides these "speakers" you are wanting to buy, expect to hear your music in quite a different light...which might be quite a bit worse (like really bassy, etc). But that'a a whole other topic that you can research in these forums.
EDIT... I see you don't want headphones... Well, I won't convince you.
Therefore, I'd go down to Radio Shack and see what their best is for $100. Their "optimus" series was half decent, but those are probably long out of production. I think if they still sell speakers, they ought to have the best available for $100. seriously....
One last thought... hit some yard sales, or look for some stereo speakers (like suggested earlier)... maybe in the paper..or Ebay.
I've seen some old JBL speakers go for about $200/pair. Some old L100 series. Realize, maybe 25 years old, but they'll be killer speakers for $200..
welp, out of ideas. You can thank us all later... !!