Hi and Welcome,
Thought I would add something from a relative new guy, although sooner or later that excuse will wear thin for me.

There are two ways to compare speakers before you buy them. The most obvious being, listen to them and decide what you like. Yes, there are technical things that a professional will listen for in order to 'define' it's quality but the bottom line is, will they make you happy.

The other takes some research and understanding. I did a lot of web reading on understanding sound and understanding how companies test and document their speaker specifications. A well respected speaker company will publish all of their electronic specifications and they will also include stats on how the speakers behave across the audible spectrum. You can learn to tell a good speaker from a bad speaker this way but again, people have different tastes when it comes to the finer details.

In short, when on a limited budget, do a little research but don't get hung up on the details. If you start to scrutinize, your budget will start to depress you. Audition as many speakers in your price range as you can. If you can audition them in the same listening area, that's definitely preferred.

Finally, I don't own M3s but I can tell you that if the quality per dollar is compatible to the M60s then it is definitely worth ordering them for the 30 day trial. Listen to others during the trial then choose the one that suits you best.

With great power comes Awesome irresponsibility.