I think investing in a property in Mulund would be a very good option because most of the people prefer buying a property within Mumbai Municipal limits. Secondly, in times of recession the worst areas that get hit are the suburbs like mira road, bhayander and so on.
Therefore i would advise you to go for any property in Mulund. In case you are looking to find some property in this area then I would suggest you to try out a site called www.quikr.com
It is a free classifieds site wherein you will get lots of properties listed for different areas.
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I would opt for Mulund 1 room. and I wont wait too long, does not look Virar is going anywhere, the prices have been steady for last 7 years and they will remain that way. However there are lots of other factors to consider, where is this 1 room, what kind of market you expect in future, as far as I know. its not the niche market, these days the 2 bedroom houses seem to be selling like hot cakes while 1 room is a subprime market. Mulund is in Mumbai mahanagar palika (part of it in Thane_ so do a study of that as well.