Wow, this is quite a topic hey. I'm not the OP, but did chime in a few pages back.
For many years previous I've been an avid home-recorder, and smashing out sub-standard songs left-right-and-and centre - using a knackered Apogee MiC and trusty garageband on my iPad. Oh to hear the music that I made ....... monitors - pahhh, the good old iPhone free headphones.
Why, because I love making music. That's all. I know that I'm never going to make a £ out of it, and I'm not doing it for the fame or the birds - just to give me something to do when I get home from work and don't want to watch some murder/mystery that the Mrs is watching on the TV.
If I'm being 100% honest - previously when I was reading forums / posts on various home recordings 'things' and when someone said about 'studio monitors' - I honestly believed that they were talking about what you looked at when you made your music - y'know, a computer monitor. This confused the hell out of me as I couldn't see the benefit of 'some decent monitors' - it wasn't as if I was intending to edit HD Photography or anything.
It was only recently that I learned that 'monitors' are what I usually call 'speakers'
So, when I got a iMac for work - and then thought that I should upgrade Garageband to Logic Pro X - I was missing the speakers (for my home-studio). So I went in to the local music shop and grabbed the cheapest ones that I could find - that was my only criteria - the cheapest. I'm lucky enough not to have 'many' budget constraints, and this was coming out of my 'smile money' account, so yes, I could have chosen some really expensive ones.
The reasons why I bought the ones that I have: 1) I thought that I should as that's the norm 2) They were literally the cheapest I could find 3) I though that anything would be better than listening through my iPhone headphones.
Having said all that - in about 5 years time when I've started to understand Logic, and what mixing/mastering is all about (I've watched youtube videos on this - and it's like a total foreign language to me at the moment - what happens at different frequencies etc) then, I'm sure that I'll upgrade as the ones I have wont suffice.
"Go to the local music shop with a cd and an SPL meter. Put a 200 Hz, a 2k and a 10k test tone on the CD. Add to that a sweep from 200 down to 20 (the top end is usually not an issue)" means absolutely nothing to me at the moment - I literally don't have a clue, apart from the 'CD' part.
I suppose it's all down to what point you are along the journey, and where it is that you're planning to end up.