I’ve been shopping for a similar item and couldn’t believe the Lotus price for the front section of the cup cage, must have at least 400% mark up on it.
In the end I’ve gone for a safety devices 2 piece bolt in full cage, with new hoop. More work than a bolt in front section but less money.
Plans motorsport offer a good weld in design attached to an existing T45 roll hoop.
HotLap also do a full weld in cage with integral replacement hoop.
There seems to be a lot less cage options for S2 cars. As Sean says the only alternative that seems to exist to Lotus for a bolt on front section is Hoffmans.
Is your existing roll hoop a T45 factory option one? This is needed to attach the front cage section as the standard CDS steel roll hoops don’t have the mounting bosses.