I've found 1 word that starts with prefix de, in total 9 letters. taken in .com available on the rest.
Would you recommend to go for it or not?
Which particular extensions i should register?
I'm on a very very very tight budget, and i wouldn't register it unless it's guaranteed to sell short term.
If you are on a very tight budget I wouldn't do it.
It can't be that great a word if all the other extensions are still available, and that means you may have trouble finding a buyer for the quick flip you are hoping for. Just my humble opinion.
I agree with obmenneg.com. If the word is not occupied in other zones, then there is no special need for it.
Even if it's attractive, how likely is it that you'll be able to sell it quickly and expensively.
In the end, if you like a domain name, register it in any zone, and develop your project on it.
Even if you don't sell the name, you'll be doing something interesting.