Adam,
Your questions are very welcome as that's what this forum's all about ... Sorry to keep replying like this though ... ;-)
Glass tops are expensive as the moulding is difficult to produce in glass. The major player's catalogue's have replacements in plastic or cheaper glass units. check the catalogues for Eckler's, Mid America and Corvette Central, then run that product by J&D Corvettes as they're cheaper but you need to know what you're looking for.
As an Aussie alternative, contact Ralph Moore from Ralph Moore's AutoGlass (029667193) as he may have just the glass or some 2nds that you can charm him out of. Tell 'im Rebel sent ya and ask him to get a move on with my ttop rubbers will ya, I've been waiting for ever .... :D