People make too much of this. It's not nearly as important what ammo you use to practice with as long as you practice. If you practice enough to become proficient with your weapon of choice, when you feel like you're one with your handgun, it doesn't matter what you shoot through it, you'll hit what you shoot at.
If can find practice ammo using the same bullet weight as your carry load, then you may as well buy it rather than something else, but it isn't critical that you do so. Shooting your actual carry ammo, which is undoubtedly more expensive than practice ammo, isn't a good use of your resources.
Shooting 200 rounds of practice ammo will do you a lot more good than 50 rounds of your favorite JHP.