amigastore.eu has the ACA1220-16 for 88.52 Euro.
However a small RAM expansion like this could still be useful. I've found a couple of games/demos that slow down or stutter with my ACA1232-25 attached to my ACA500. Disabling the ACA1232 seems to fix the issue but the lack of RAM causes some issues with WHDLOAD.
The majority of games/demos work fine however.