I recommend night sights. Most if not all night sights come in medal casings.
I had a bad experience where the plastic sights move as I shoot. After every
mag, the sights moved. I tried relying on just the front sight for a few mags, and after about 3 mags, the rear sight was actually hanging off the side a bit! I understand this is not a regular occurrence, but it does happen and that's why I don't trust them.
I have also pushed a lot of sights, and over 50% of the time, the factory plastic sights break when pushed off.
If you are dead set on the sight picture of the original Glock sights, you can order steel sights and have them put on. The only problem with the steel sights is the front site is staked on, rather than screwed on like most sights are now days, so you will have to find someone who can stake them on.
Below is a link I just googled. For the Glock 30, you will need the 6.9 rear, and of course a front.