I don't really think they are especially cheap, most of them are ok as rolling shells but that's pretty much it.
I sold a solid and running 1300XL Mexico replica for 3k a year or so ago which just needed a bit of tidying really. It had a 1600 mk2 Ghia engine, single decambered leafs, Capri front struts and decent interior amoungst other bits.
Interesting find though.