I paid $22 for the last SX610 I won on eBay and it came with a nice SX810 GT long cage and an SJA 102 front. I don't think it was more than a year ago. The SX610 just needed pulleys, so I took them off of the SX810 that I have no use for. The SJA 102 is the front you need for an early PX10 because it has a housing stop.

You'll sometimes see NOS SX610 and SJA 102 derailer sets sold on eBay as Gipiemme Sprint.