Story time: I went through this last year when I wanted to take better pics of my kids without breaking the bank. I know people love the options mentioned in the first couple replies, but I wanted to see if I could go even cheaper and still get that 'pro' look. - Viltrox AF 56mm f/1.7 Sony E vs Viltrox AF 56mm f/1.4 E: I actually tried both and honestly, the f/1.7 is such a hidden gem. It’s SUPER cheap and light, making it great for street stuff. The f/1.4 version feels more 'pro' with the metal build, but the AF on the f/1.7 felt just as snappy on my a6400.
- Yongnuo YN50mm F1.8S DA DSM II: I also checked this one out. It’s insanely affordable, but the build quality felt a bit toy-like compared to the Viltrox stuff, so I didn't keep it. I literally ended up staying with the f/1.7 Viltrox tho. It handles the eye-tracking perfectly and the bokeh is reallyyy creamy for the price. I’m super satisfied with how it turned out and it didn't hurt my wallet at all. Good luck with ur search! 👍

yo! i feel u on the kit lens struggle—it basically kills the vibe when u want that pro look. honestly, i've been shooting with the a6400 for a while and I'm super satisfied with my current setup. If you can stretch ur budget just a tiny bit or find a used deal, the Sigma 56mm f/1.4 DC DN Contemporary Lens for Sony E is hands down the king. i was worried about the lack of OSS too, but since the a6400 has such great high ISO performance, i just bump the shutter speed to 1/200 and the shots are tack sharp. the f/1.4 aperture creates that creamy bokeh that the Sony E 50mm f/1.8 OSS Portrait Lens (SEL50F18) just cant match. basically, the sigma is sharper wide open than the sony is at f/2.8. That said, if $350 is a hard limit, definitely look at the Viltrox AF 56mm f/1.4 E Autofocus Prime Lens for Sony E-mount. i tested one recently and was actually surprised... the autofocus is way better than the old reputation of third-party lenses. it keeps up with the eye-tracking really well for kids running around! id avoid the sony 50mm unless ur really strapped for cash. it’s an older design and the motor is kinda noisy for video or quiet street shots. for the best value, definitely hunt for a used Sigma on MPB or KEH. it really makes the a6400 feel like a different camera!! good luck with the choice tho 👍

^ This. Also, I have spent about six years jumping between different lens brands on my Sony bodies and I have been very satisfied with how far things have come. I remember when we basically had to pay the "Sony tax" if we wanted reliable eye-autofocus, but the third-party landscape has changed everything tbh. In my experience, the trade-offs usually look like this:

• Sony glass often feels the most "plug and play" with things like in-camera lens corrections and video AF transitions.
• Third-party contenders usually give you a much wider aperture for the same price, which is where you get that creamy look you are after.
• Build quality varies, but I have found that the metal housings on some newer budget brands actually feel more premium than the plastic Sony budget primes... I have no complaints with my current mixed-brand bag, but I do have a couple of questions to see what fits you better:
• How much do you value portability versus having a larger, faster lens?
• Are you mostly shooting single subjects, or do you need something wide enough for group portraits too?

sooo, I feel u on the kit lens struggle. honestly, i tried to go the ultra-cheap route with a random brand I found on sale and it was sooo disappointing. The image quality was okay i guess, but the autofocus felt like it was from 2010... definitely couldnt keep up with the eye-tracking on the a6400. it basically ruined my day out with the fam cuz I missed all the candid shots. for your situation, i'd really look into the used market for a first-party prime. if u can find one for under $300, it's usually better than gambling on a brand-new budget brand. but before u buy, I have a couple questions: 1. are u mostly shooting wide open for that bokeh, or do u care more about corner-to-corner sharpness for street stuff??
2. is having weather sealing important to u at all?? i mean, the ones u mentioned are solid, but i've found some third-party glass has weird color fringing—that purple glow—that’s a pain to fix. basically just wanna make sure u dont waste ur money like i did lol! gl!!

I totally agree with the point about Viltrox—they’ve really stepped up their game recently and the price-to-performance ratio is getting insane across the board... honestly looking at the market right now, it's a great time to be a budget shooter because brands like TTArtisan are finally figuring out the autofocus thing. If you want something even more wallet-friendly than the Sigma, definitely look at the TTArtisan 56mm f/1.8. It’s surprisingly sharp and the AF motor is actually pretty snappy with the a6400’s eye-tracking, which is kind of the holy grail for cheap lenses!!! Another interesting option that people often sleep on is the Samyang AF 45mm f/1.8 FE. I know it’s technically a full-frame lens, but on your a6400 it acts like a ~67mm which is a really sweet spot for portraits that aren't too tight for street stuff. It's super lightweight—basically feels like a toy—but the glass is legit and the bokeh is really smooth. I’ve seen them on sale pretty often within your budget... just something to think about if you want a slightly wider field of view than the 56mm but still want that f/1.8 blur! Just make sure to check if they need a firmware update via a lens station, sometimes that fixes any minor AF hunting issues on the newer Sony bodies.