does anyone know anyone that makes. These

 

The actual 'box is what makes it sequential, not the shifter... ie. It's not an "add-on" to a standard box.
A full race gearbox with sequential shift is more than a few pennies and usually only worth it for serious competition.

 

Sequential Shifting System | SUBARU Impreza WRX STI

and a similar system is available online, but i dont have the link here at work, can dig it up at home though.

 

you can get a bolt on there is one for a 6 speed needing something that is capable for a dog box