I know that majority of commuter bikes and even some bikes above 80k don't get a proper horn. Manufacturer gives horn just for the sake of it!
I don't think you'd be having any problems with spending money on the horn (upto 500 bucks) and would consider other the efficiency of the horn instead.
You precisely want : An OEM
Sounding Single Horn (Plug and Play without any wire cuts or relay).
You can have a look at Pulsar horn (UNO Minda make) which come as pairs for 400 bucks. You can ask the shopkeeper to give a single horn. It has the OEM
tone (with slight sharpness to it) and would be a direct plug and play for your bike. If you are not going for a relay (which isn't needed for a single horn), you'd have to shell out maximum 250 bucks and a simple DIY can be performed to swap the horn. I will guide you through the DIY if you want.