Akai Professional EXM128 - 128MB Memory Upgrade for Mpc500, Mpc1000, Mpc2500 $13.99 + Free Shipping with Prime
If any of you own MPC-500 MPC-1000 or MPC-2500 this is a great price to update your ram.
MPC will only use half the RAM and can not use a card bigger than 256 for 128MB max RAM. I was worried this was going to be a 128MB card and show up as 64MB in the machine. I was wrong. I can confirm it works and shows 128MB in my MPC-1000 with JJOSXL.