When I replaced the slave cylinder on my truck it was with the OE part from Burt. IIRC it was price competitive with aftermarket (I want to say about $45). Sometimes you get genuine Aisin parts from NAPA and IPW, though, so it's probably worth checking.
Getting at it is a PITA, but it's not the worst job ever. I wouldn't rule out a hard line, they can rust, too. I have one of those power bleeders that might be handy pressurizing the system to look for a leak. Not sure how I'd get it to you any time soon, tho.
'91 Toyota Pickup
'09 Kawasaki KLR650
'12 Gunnar Rockhound 29
"They say the test of literary power is whether a man can write an inscription. I say, 'Can he name a kitten?'" -- Samuel Butler