Ford Ranger 2001
The problem with the vehicle is that it won't shift into gear easily and smoothly. It started occurring just this last Friday or Saturday (2011-06-24 or 2011-06-25). I was driving around 35 MPH, slowed down to a stop at an intersection, and when I put it back into 1st Gear to begin driving, I had extreme difficulty shifting the gear. I cut the ignition and started again, was able to put it into 1st Gear and made it home by coasting (getting into any of the other Gears was just as difficult, fortunately I was in the neighborhood). Following this, I tested it while parked the next day. Same issue. Then I tried double-clutching, which seemed to help out, but I only did it parked, since I didn't want to strand myself on a road (I'll take that risk when I go to a mechanic, though).
I've read this on the Car Talk Discussions (http://community.cartalk.com/discussion/741209/hard-shifting-honda-crv/p1) and from my years of listening to Car Talk, I'm pretty sure it's the clutch (master/slave cylinder) and I'm also aware that it could be the transmission fluid requiring a change. I haven't changed the transmission fluid at the 60K & 120K interval per Ford's suggested maintenance schedule (I got it around 50K-60K from a dealership, so I'm not sure if they may have done it preemptively).
A couple other details. For the past year or so, I've been driving 100 Highway miles for 4-5 days a week, for work (50 to work, 50 back home).
Are my assumptions right, or is it possible that my whole Transmission is getting ready to go? Are there any other details I should provide?
Thanks in advance
Edit: I'm going to take it into a mechanic, as noted above, but I was wondering how much it should approximately cost to do the transmission fluid and then how much it would be to replace the entire clutch (even if it's just the slave cylinder, I'm going to follow Tom & Ray's advice on replacing the whole thing once they're in there).