I need more RAM in my A500.

[SilvrDrgn]

Google:  AdRAM540

Then check eBay or other Amiga sources.

(Note:  I have one these and its companion 560 in my A500, and it works great.

[SilvrDrgn]

The AdRAM 540 will take you way beyond 1Mb. The 540 and 560 together may get to 4Mb. The Baseboard is another bigger than 1Mb expansion for the A500. Just because they don't use SIMMs doesn't mean they are limited to 1Mb!!
An ideal setup would be a mega midget racer with a 4Mb SIMM on it. There are a couple of accelerators besides this one that allow more RAM.
Here are the specs on the AdRAM cards: http://www.amiga-hardware.com/showhardware.cgi?HARDID=1015
Looks like 3.8Mb is the most you can get from this trapdoor expansion.

Actually, AdRAM 540/560 combination will take you to as much as 6MB of RAM in a properly configured A500.  I've got that and a little more in my A500 since I also have a "sidecar".  See here - http://mikerye.homeip.net/about_my_computers.html