Get a 68030 accelerator and make sure you get at least 4MB of RAM to go with it. A 68040 doesn't provide a noticeable performance boost and will cost a great deal more and that's if you can even find one. Get a 2.5 inch internal IDE drive as well. Anything over 4 GB in size will have to be partitioned into multiple logical drives as AmigaOS 3.9 and below don't support boot partitions greater than 4 GB.
SoftHut and AmigaKit are great places to deal with. If you have extra money to burn, get a FF/SD too. They're very rare and hard to find but well worth it if you want to use a VGA monitor.
