You can upgrade an A500 fairly commonly to 030 speeds, several companies made such expansions and they are available from some amiga dealers.
You would need that, memory, 3.1 chips, some kind of hdd expansions...just to get a bare minimum.
The problem with the A500 though, is its virtually impossible to get the graphics upgraded, and it needs that badly....some hacks are available for adding a ZII in a tower case.
Anyway, you are talking big expense for little gain.
Better to get an A1200 with 030 and hdd, you might get lucky and get one near your budget.... AGA graphics are still not the best for web browsing, but thats the best amiga for a little over 100, imho.
Don't even think about web browsing on an OCS machine without a graphics card...please!
