Buying Nikon D3100 dSLR from grey market would be fine?

Do Nikon dSLRs break down quickly or in less than 2 years of usage? I mean you won't get 2 years warranty and will get the same camera for a very low price around 5k less if bought from grey market. What would you suggest?

In my experience, cameras (just like other electronic devices) are likely to break down more frequently in the first few months of use than at any other time. If they work for a few months, they probably won't break down for years unless mistreated. Both my D70 and D200 had to be returned for service within the first year or so, but have in general been extremely reliable, and have had a lot of use, with about 10, 000 exposures or more per year.

Gray market cameras are reported to be very difficult to get repaired - you're often stuck with the store's warranty rather than the manufacturer's.

The standard Nikon warranty is 1 year - I've never purchased an extended warranty on cameras.

You either pay now or pay later.

The cost of getting a gray market camera can be quite expensive since the Nikon importer will NOT touch it and you will have to use a local repair shop, which may or may not do a good job.

Here in the States, the difference in cost between a gray market and authorized camera is not more than about 10%.