You can buy materia from the guy in the shop in the top right, but there’s isn’t anything new. You can’t get back in the Honey Bee Inn either. You can go back to Don Corneo’s mansion and pick up any items you didn’t get before, and free a guy in the basement. Go to the second screen and enter the building on the right. Talk to the guy on the left and buy three batteries for 300 Gil, you’ll need them. You can buy weapons from the guy on the right.
Go north a bit from here, and you will see some kids run to the right. Follow them and talk to the kid by the wire. Climb up it after talking to Tifa and Barret. Go up the wire until you jump off. Go south and east towards the yellow object to the right. Put a battery in it. Head up after the propeller has stopped spinning. Jump down onto the track by pressing O. Put another battery in the box and climb up the barrier. Climb up the wire. You’ll come to a swinging bar, you need to press O at the right time to make the jump. It might take a few tries. Try to jump just as the end of the bar hits the dangling wire you climbed up and as the squeaking noise is stopping. Once you’ve made it go north to the next screen. Climb up the wire you are on until it goes up then down, follow it to drop down. Put the last battery in the box to get an Ether. Go down a screen and jump onto the bar again. When you get to the next screen again, just continue up, instead of dropping down, go up, then climb down onto the large wire and continue up.