looking for a specific part – a brake cable splitter

I have called three bike shops and none has it in their distribution network

I am installing an aero bar brake lever on a touring bike which also has "normal" flat bar brakes. I will install it just for the rear brake.

so I need a cable splitter (rim brake bike) , but I am having trouble locating one, I found these:

– Porkchops BMX Porkvert, but I don't know if this would work with a V-brake touring bike or just BMX

– J Tek lever and splitter, but it's not available for sale
– Problem Solvers cable doubler , I think this one would actually work fine, but it costs $60 (not a no-go, just a bit pricey)

Thanks for the help !!