Firstly, your equipment is good enough despite what you think or have been told!
I’ve seen some amazing images taken with an entry level DSLR and kit lens (regardless of the make). Even the most expensive equipment isn’t going to get you anywhere without passion and patience.
Secondly, look for second hand equipment online or at your local dealers. You’d be surprised how affordable “outdated” professional lens and camera models can be. Some big name lens designs haven’t changed in decades because they are that good. So there is no need to sell the house to buy the latest professional piece of equipment.
Chad Wright explains that to be a Wildlife photographer, you need patience, timing and you do not have to go out and buy the most expensive camera. This self taught lesson, can also be used for whenever you go to the zoo or if you find yourself on a safari trip.