I’ve got a Westbrook cr1 sl and I’m in the process of getting some new handbuilts.
Pacenti SL23s, Aivee SR5 hubs, CX rays. Should come in just under 1400g and a bit over £500.
I was looking at C24s but decided to go handbuilts due to hearing the c24s weren’t that stiff and also the rims are expensive to replace. Mavic Kysirium SLRs look great but as you say are expensive (plus are quite squeaky). Wiggle have Campag Neutron Ultras for under £500; they’re pretty light.