Is it bad to use an auto ecu?You okay with using the automatic A71? They come up on eBay fairly regularly from salvage yards going for between $150 and $200. Sometimes they'll include the immobilizer and a key for the car which could be helpful if you do run into problems but that's usually adds about another $100 to the asking price.
If you're dead set on a21 manual ECU You're going to pay about three times as much and they're pretty difficult to track down.