I haven't seen any significant .net.in sales. It's not really a popular extension in the domain aftermarket.
Those are really strong keywords, and they are probably worth something to an SEO type - around high $xx to $1xx.
Other than selling them on, to make some money from them you'd need to develop them. I doubt that they would make much from parking but it doesn't hurt to test that out before you do anything else.
Probably these domains won't fetch you big bucks as .net.in extensions are least popular. Whenever you buy a domain see that you have right extension like .com or .in or atleast .co.in. Anything apart from these won't give you a great deal.