Thanks for the answers guys!
I was thinking about 300 eur. for the pair, or something more.
I have started producing from a few months, so I do not really know if this will last for a long time, I hope so but it depends on the quality and the visibility that my tracks will achieve. At this moment I have enought money to buy more expensive monitors but I don't know if it will worth it.
I think that for now I may need 2 good monitors for reaching a good quality of mixing, and than let make the mastering to an external studio.
I have to buy also an external audio card, and I want to spend about 500 eur. in total.
if you are sure that you want to dedicate yourself to learning production, then spend as much as you can afford on monitors, its definitely worth it
regarding audio interfaces, you don't have to spend allot on these, because unless you are looking for a very high end interface (pro tools, cranesong etc, which can cost thousands), you arnt going to notice allot of difference in the quality - as long as its a pro audio interfaces (m-audio, focusrite etc), with native 24bit 96khz Digital-Analog/Analog-Digital convertors, and reasonable preamps (if needed, for eg recording from mic's), then it'll do fine
Latency is always an issue, but unless you want to spend allot of money on an audio interface and studio PC, its just something you have to learn to adapt to, so adjusting the buffer to give better latency when recording, and then adjusting again to prioritize resources for more complex projects when things start to crackle and glitch...unfortunately you wont find an audio interface in your price range which will allow you to have true Zero Latency with very complex projects, 3-5ms is about average, you might get 1-2ms with simpler projects; its not to bad really unless you are recording live instruments or vocalist with lots of live effects in a very complex project, in that case you would probably want to look at a pro tools setup, but as you have just started out, that option is probably a way off yet...monitoring is by far the most important thing to think about right now, that is where you will get the most benefit while learning to mix down (but don't forget about room treatment aswell...this hobby gets expensive lol)