If you have a problem you have to ship it back. You may want to get it locally. If it's a stock engine, then a stock clutch from NAPA, pep boys or advance should hold up fine.
Why replace the master cylinder?
Some clutch kits from pep boys (napa, advance, one of them) ( for 89 xj) comes with the slave. Yours may too.
From napa online ... for a 92 wrangler with a 4.0. They should have it down at the middletown store.
Beck Arnley Clutch Pack - New
Usually ships in 24 hours. BA0616182 $ 249.00
Includes Slave Cylinder & Integral Release Bearing, w/ 267mm Diameter Clutch Disc
I'm sure advance and pep boys have similar deals.