it does not come from the cabinet and FTTPoD is for mainly business use hence the cost
as a business user you need to post here as this is a residential forum https://business.forums.bt.com/
FTTPod is quite a niche product and not many providers offer it ( as far as I know BT don't ) , so you would have to enquire with a provider that does....the old way of pricing FTTPod was based on distance bands from the Aggregation Node ( not the FTTC cabinet ) 0-250m, 251-500m, 501-1Km that sort of thing , but now it's a more bespoke estimate for your individual address, you can get a 'free' non contractual desk based estimate, to get a ballpark idea of costs , if after receiving that, you still want to proceed I believe it's £250 to get the contractual cost of provision, if you don't proceed you don't get the £250 back, if you do its subtracted from the cost of provision .
Other forums have threads about people who have been down this route , desk estimates over £10k seem quite common, and many who got a previous 'banded' estimate ( and didn't proceed hoping the new way of pricing would be cheaper ) complain that the new way of costing is considerably more than the old