Building SMPS using L4960: How does the choice of inductor affect circuit operation?
If you can't find one, it's quite easy to wind your own with a suitable toroidal ferrite core. 150 uH is quite a low value and won't require many turns. You need to ensure that you use a wire gauge that can handle 5A, of course. Suitable cores are available from most component suppliers, and the manufacturer's web site will have design details. I've wound larger inductors using a pot core for an MCU-controlled switching power supply without any problems.