I want an autoharp. It's a harp that automatically chords with button presses. Pretty expensive, but it's an instrument that can be played withiut risking loss of sensitivity in the fingers (for braille reading). Your brother might be interested in something like that.
An audio book device with a subscription for books might be nice.
The Bop It is very easy to play without sight, especially the more classic models.
He might appreciate some high quality headphones for listening to all his iTunes music and audio books too.

Blind people are just people. What would you get him if sight weren't a barrier? Maybe we can help you adapt your gift idea. Lots of other considerations matter more than vision, though. Most importantly, what does he like? If music is his thing, what about the an instrument, like a hand drum or ukelele? They can be bought for under $50. How about a pair if concert tickets and take him to a local show? How about a nice set of headphones?

Might like a Google Home Mini or Amazon Echo Dot and they are pretty cheap now....

This might already be folded into iTunes, but an Audible subscription will keep him knee-deep in literature.

There is some recent evidence that active reading (braille) improves comprehension and retention over passive reading (screenreaders/audiobooks), which is relevant in light of technology heavily favoring the latter. So maybe a trove of braille ebooks.

Finally, this isn't for everyone, but I know people have enjoyed guided adventures like skydiving, bungee jumping, parasailing, climbing, and so on. And it could be good to promote mobility since that becomes a big challenge as someone goes blind.

soI am 27 and completely blind and my brother and I have a cool relationship. He has given me some action figures and I have started a collection of Marvel stuff because of him.

There are several computer games for the blind that you can research and have mailed to you.

You could craft something if you are into that sort of thing, again my brother once made my favourite silly prop sword from this fantasy show I liked.

I know he does not read Braille, but you could get him a t shirt with Braille on it.

One thing my family sometimes does if they don't know what I want is they give me vouchers for little things, like a shopping trip with them, a movie, going to a restaurant, etc. If you know of any hobbies you want to share with your brother, or things he's wanted to do for awhile, or things he just likes to do (or if you want to make sure you're buying him the right gift lol), then this might be a good idea.

The new Kindle is pretty blind friendly paired with bluetooth headphones.

I love shopping at 64 Ounce Games for adapted board games if that's something he might be into.