Oh, and when you say "wearing out" - what do you mean?
I've routinely taken the keys out of mine, cleaned everything, and put it back together successfully.
It's a little ugly - membrane keyboards are not the simplest to maintain - but it can be done.
If you've NEVER cleaned it out, that may be all that's needed.
Get a good quality key puller and lift them out carefully.
Dump the keys in a weak solution of dish soap and warm (not hot) water and slosh that around a bit.
Then take a Q-tip and some soft copper wire (my favorite tools for this) and gently dig and scrape and prod and otherwise coax out all of the accumulated gunk everywhere you can find it.
Use a can of air to blow out what you can't reach.
I usually finish off with a good spray of CRC's QD Electronic Cleaner (please, g-d, you unplug it first) and then another pass with the Q-tip.
Let it dry, carefully reinsert the keys until they click in place.
I've never tried to pull the joystick, but you can rotate it around and clean the exposed bits pretty well.