The el cheapo way to add a quick 8Mb is to throw an old ZII 8MB memory card in. I think the best option is to get an old GVP HC+8 card and populate with 8 30-pin 1MB simms. This will be faster than the old dip-style 100+ns boards such as an 8Up! or Supra board but slower than the motherboard simms:( It also gives you a slow SCSI interface). I recommend disabling the autoboot jumper on the board or be prepared to wait 3 minutes for the A4000 to boot. The Dataflyer RAM8 board is another ZII option that takes 30-pin simms, but probably slower than the GVP.
Of course, a real 32-bit accelerator with its own simm slots is the way to go, a Cyberstorm or a WarpEngine, but these are not cheap unless you get real lucky.
