In order of price low to high, and in my opinion quality, low to high.

If you are in a very small space.

1.M-Audio BX5
2. Focal Alpha 50
3. Focal Alpha 65

Typical bedroom /small living room

1. M-Audio BX 8
2. Presonus Eris 8
3. Focal Alpha 65
4. Focal Alpha 80

The Focal Alpha 80 maybe slightly above your budget, for a pair.

I think the Focal Alpha 65, and the Presonus Eris 8's are really great choices. Quite decent for the price, and definitely the best picks for your budget from lots of auditions I have done on these monitors.

In a smaller room the Focal Alpha 50's are also very good.

Let me describe these.

Focal Alpha 50 - lovely tight sound but with not too much bass.

Focal Alpha 65 - excellent sound for the money, especially for a small room, without overemphasizing the bass. - This would be my safest recommendation, if you are buying new. - It has an excellent sound.

Focal Alpha 80 - Excellent bass - very real life image - like listening to the performer - could seem a bit dark depending on what you are familiar with listening to. The Focal Alpha 80 will definitely need careful placement to avoid room corners, or close placement to walls over emphasizing the bass. With these I do not think a sub woofer is necessary. I did not find the bass on the Focals extremely accurate, it was deep but not absolutely precise/tight in the bass.

Presonus Eris 8 - Not as much bass as the Alpha 80's, but this kind of sounds a bit more hi-fi, somewhat similar to some high end headphones that I have listened to such as the AKG 702's which do not have too much overblown bass. You may consider adding a sub-woofer at a later stage, if you think you need more bass. When played loud they are more than bassy enough though.

Overall the Focal Alphas, definitely have a "transparency", and in my opinion are the most undistorted monitors below 500 euros (approx). Which give you a level of insight into the music that is closest to "higher end professional monitors" which cost a lot lot more money.

Whatever you do, you will need to learn the speakers signature, no matter what you eventually buy. This takes a while. A good way to do this is to listen to a lot of music that you know very well or like from various artists and genres, so you know what "normal" sounds like on your monitors.

Far more important than the monitors is :

1. Learning their signature

2. Placement in your room, adjusting this to get the very best sound in your own environment. Where you sit(distance wise) in relation to the monitor is vital.

3. Some acoustic treatment, and here I do not mean expensive panels or panels only. Soft furnishing - drapes, carpet, can help tame reflections/echos in your room, to give you a more direct sound, from your monitors, with less of the reflected sound muddying things up.

4. Playing your audio at the right volume due to Fletcher Munsen effects on how humans percieve frequency....

If you ever get a perfect good pair of secondhand Alesis M1 MK 2's (they are no longer available new), and block the ports, amongst other tweaks, those come well within your budget. I would still recommend these over all of the above, because its easier to block their ports, and there is very little internal equalisation the manufacturer has put in to attempt to improve the sound, i.e what you hear is predominantly the effect of excellent physical design and materials rather than DSP/EQ tricks, and they use soft dome rather than metal tweeters like the Focals, for less fatigue on your ears. There is no EQ at the back of this so you are forced to use placement to derive a good sound. i.e rather than put a plaster on your room sound by using EQ controls, with the Alesis I was forced to sort out whatever problems my room had, cos it had absolutely no EQ adjustment.

It took me a while to learn how to setup the Alesis properly, but it was absolutely worth it eventually.

I restate - you will need to learn every speaker, no matter which one you buy.

I warn though, unless you are playing them at a volume which is a bit louder than you should, the audio you will get from all of the aforementioned monitor is not one with a lot of Chest thumping, room shaking bass.

For that level of deep bass, you will need a sub woofer. For a small room, not advised. So you will need to learn how good bass sounds in your room, without it thumping you in your torso.

I have left out some monitors, the KRK's - just not in the same league of accuracy as the Focals, The Alesis when set up properly, and definitely not as good as the Presonus Eris.

The Yamaha's had this smiley EQ "signature" - slightly heavy bottom and a bit of sizzle at the top, even when EQ's are set to flat. They are ok if you like that hi-fi sound, it helps some people, but I value absolute neutrality. The last thing I need is my monitors clearly altering the sound. As much as I wanted to like the Yamahas - great price, their slight sizzle was obvious especially on acoustic instruments and voices, and I felt I was not being told the truth. Sounds like some PA's... They were great in comparison to what monitors sounded like in the mid noughties, but the Focals have clearly moved things up a notch.

If I had enough money, I'd get the ERIS 8's, Focal Alpha 65's and the Focal Alpha 80's - as well as the Alesis, in addition to one really high end monitor, and use these lower end monitors as part mixing or reference in other rooms, as they give a really good representation of what mid range to good music systems, will sound like, and I would expect that if anything sounded outstanding on all five, there's a very high probability it would sound good anywhere else. - Wishes!