I hear about this a lot if not every other day... More and more people are getting into the fighting game scene. They find these sticks everywhere for cheap from yard sales to eBay.. They are great starter stick that when upgraded, can last years... The Madcatz SE/Brawstick. They come unfortunately with cheap parts (no offense to Madcatz). Here is a list (There is no comprehensive list for this stick as you set the limit on this one)
Those Stock Buttons... JUNK 'EM!!!
You can use any 30 mm button whether its snap in or screw in. If you are using screw in buttons instead of the snap ins be sure that you get the clear Seimitsu nuts. (http://www.focusattack.com/seimitsu-k-n-30mm-clear-screwbutton-nut/) Otherwise the Sanwa won't fit with those orange "pepsi cap" screws they come with.
In addition to replacing the imitation JLF stick with an official stick (http://www.focusattack.com/sanwa-jlf-tp-8yt-joystick/) you can even go further and add more tension and actuation to your sanwa stick with the Kowal actuator (http://www.focusattack.com/kowal-1mm-oversize-actuator-for-sanwa-jlf-series-joystick/) and sanwa 2lb spring.(http://www.focusattack.com/2lb-tension-spring-for-sanwa-jlf/) and for more angles, an octagon JLF gate
(if you like having 8 sides as opposed to 4 which comes stock)
Balltops are mostly cosmetic but are a nice splurge that won't set you back too much (http://www.focusattack.com/seimitsu-lb-39-bubbletop-red/) Seimitsu and Sanwa Balltop and JLF Battops (with adapter) WILL fit the Seimitsu or Sanwa stick thread.
Replacing the rubber feet with sturdier feet is also a nice budget update to reduce slipping in the lap or table
http://www.focusattack.com/35mm-aluminum-anti-slip-joystick-case-feet-set-of-4/ (follow http://support.focusattack.com/entries/87964496-Putting-Case-feet-on-Madcatz-Brawstick-SE for steps on putting these in)
ISSUE WITH TURBO ON THE SE
I forgot to mention is that is there a way to disable or just unplug the turbo functions. I say this because when tapped ever so slightly a random button goes turbo, or they lose function temporarily.
MarkMan responded to this one 4 years back in shoryuken tech talk:
"Make sure it is unlocked and plugged in. Once it is plugged in press and hold the turbo button down. After about 8-12 seconds they will flash once and all the lights will turn off.
This should disable turbo settings." - http://forums.shoryuken.com/discussion/122956/my-se-turbos-are-stuck
If you want a more permanent solution, you could get a PS360+ pcb (http://www.focusattack.com/akishop-ps360-multi-console-joystick-pcb/) and remove all the connections to the PCB and just use start +select to activate home
This is just my recommendations; the sky's the limit on an SE/Brawstick. You can see that the SE stick is a very accommodating stick.
Basically most commercial Fightsticks (Madcatz, Qanba, Hori (VX and V3 are bit more tricky but can accommodate), etc. can handle any of these upgrades. But for the buck, this is a great starter that can phase upgrades. The SE / Brawlstick can last a while and can be passed on to the future little fighters.
We look forward to seeing your handiwork so please share your pictures on our FB page.