The ZFQ Retails at £6495 = $9600 US at todays rate
Remember that the ZFQ fits with the standard 157 tooth Ford flywheel, Ford 10.5" Clutch, standard Ford Starter and off the shelf pilot bearing.
Other transaxles need adapter plates special flywheels and clutches, need upgrades (LSD)or flipping, output shaft adapter or stronger input shafts and mounting brackets/plates. Have tricky gear change solutions, flywheel match balancing issues, special pilot bearings ect. Most other transaxles give you miss aligned drive shafts and a high engine position or stick out the rear of the car or are too heavy.
ZFQ=65 Kgs
Rickardo=95Kgs
So to sum up you can spend a lot of money trying to fit a second hand transaxle and give yourself a lot of extra man-hours and headaches and achieve a poor ill driving car as a result, I know I have don it myself and paid the price with a snapped input shaft on a Renault 30 tranny on one of my trips to Le Mans. Not to mention the GTD cable gear change (talk about stiring your tea)
Regards
Chris