I have tried to see if my GTX 960m supports VR and sadly it seems I need minimum GTX 970m, still I have seen videos that if you overclock your 960m you can get a decent 115 frames. My question is, can I still develop games for the Oculus Rift in my 960? I can't afford now to buy assets, oculus and a new laptop.
Not easily, if your system can't support the hardware, you will encounter problems when trying to develop a game.
The Rift is a display and input device (orientation and head tracking), it's not doing most of the work when it comes to VR, you computer is. The video card is a critical part of that. The requirements for developing with the Rift are likely higher than they are for playing games with the Rift. Development code is often more resource intensive than fully optimized production code.
I expect that using a laptop with a 960m would be an unpleasant experience with the Rift. You might want to consider developing for GearVR instead because then the PC performance only impacts your development experience and not the app performance on the phone. Both the GearVR and a suitable phone can usually be found used for under $300usd total if you look around. While the Rift is obviously higher fidelity, I've seen some great stuff on the GearVR and have had fun working with it too.