Greetings!
Are we talking monitoring whilst recording in noisy situations
(and/or studio tracking) or "studio" mixing of previously recorded stuff - or all of
these?

Whatever it is I personally wouldn't use in-ears - just too many
variables and difficult to get an accurate assessment of what's actually going on.
Bearing in mind your budget, if you want a decent set of cans for mixing and
critical listening I'd suggest a listen to the AKG K240 MkII. They're open-backed so no
good for monitoring if recording in noisy environments - but very good for the money and
very comfortable.
If you need maximum attenuation of external sounds then I
like the Sennheiser HD380 Pros. Excellent isolation - better than most of the
purpose-designed 'isolation' headphones - and reasonably comfortable. I can wear mine for
2+ hours no problem - and I also wear specs. However, I wouldn't choose these for critical
mixing listening - the AKGs are much better for that IMHO.
HTH. Mike