What do you use it for? Where is the time important?
The ACA 500, 12xx, 13xx cards = no battery, no clock circuit.
Clock port here only: https://icomp.de/shop-icomp/en/shop/product/aca1221.html
ACA1221 upgrades: https://icomp.de/shop-icomp/en/shop/product/aca1221-upgrades.html
RTC module to ACA1221 (no ACA500!): https://icomp.de/shop-icomp/en/shop/product/rtc-module.html
You have to buy a ACA500 + min. a ACA1221 card, if you want a fast machine with big RAM expansion + RTC, etc.. My motherboard good basis to an expanded machine.
My motherboard with 2 MB chipRAM 110 euro, ACA500 plus 130 euro (summer 2016), ACA1221 available now, default 9 MB, 17 MHz 68020, no maprom 80 euro. All upgrades (28 MHz, 64 MB, maprom) = 40 euro.
RTC module 20 euro. Sum. 380 euro only.
I would only buy an Amiga 500 if it had the ORIGINAL clock. Now that Commodore's craftsmanship was removed, its no longer original and will probably make me late for work, I might burn dinner, backups might kick off at the wrong time etc :-(
I'll offer one American dollar.
