Another IRF9530. Not sure there is one. At 12A and 100V there can't be many possibilities. The good news is that at least four companies have datasheets, IR, Intersil, Samsung, and Fairchild. Go to one of those websites and do a parametric search for devices with equal or better specifications. If you find one which is more available or cheaper you'll have a winner.
What is your problem with the IRF9530? Wouldn't all substitutes share the same problems? They're priced at about a dollar, available everywhere, Pb-free. What's not to love about this part?
I've seem some applications (switching regulators) where the MOSFET is used as a current sensing resistor so using one with a vastly different on resistance might cause problems.
i used the mtp12p10 from motorola. that was the closest one. i was making a sequential tailight circuit for my car. its ready and works great. thanks for the help guys.