ebay always worth a go - an you can set up reminders so it tells you if something matching your description has been listed which is mega handy. You could also call local saddlers to see if they have any second hand ones for sale. Do local tack shops have ads in? You could also post your own 'wanted' ad as well as keeping an eye out for ones listed for sale?
Sure I'm pointing out the blindingly obvious to you so feel free to ignore - but you know the fits of those two saddles is v different, and just because they are adjustable it doesn't mean they can be made to fit all horses?