Toyota Repair: Transmission, major component, manual transmission

Question
I have a 4 cylinder 1995 Camry with 103K miles.  All of a sudden the other day the transmission stopped working properly.  First, it would not shift out of first gear until about 20 miles per hour.  It would eventually shift very abruptly.  When I got home, I checked the fluid.  It didn't seem to need fluid but, the fluid was black.  I can't remember when the fluid was changed.  It may be the original fluid.  I drove it to a transmisson shop the next morning.  On the way to the shop, the car acted like a manual transmission with the clutch being let out to quickly, and was jerking until I reached 20 miles per hour.  The shop called me this morning and told me that the computer indicated that there were solenoid problems.  He thought that the black fluid was indicating that there was something else going on the transmission.  He said that just changing and flushing the fluid would not fix the problem and may make the problem worse.  He suggested to rebuild the transmission.  The cost was about $2300.  Does his diagonsis sound resonable?  It's a 10 year old car, are there any other options?  Is the estimate resonable?

Thank you.

Answer
The answer to all of your questions is yes, you may be able to save some money by getting a used transmission and having it installed, most larger cities have a source of used parts available some specialize in transmissions and engines imported from Japan, these are normally low mileage units and can provide many years of service at less than half the cost of rebuilding or overhauling yours, let me also caution you about the preliminary estimate you got from the shop, it is for an overhaul that doesn't include any "hard parts" in other words if a major component like a clutch drum or shaft or the case is damaged it can drive the cost up to more than twice of the quoted figure, these transmissions have a tendency to lose the overdrive clutch, I highly recommend that if you opt not to get a used transmission, to get one that is remanufactured, that way you know up front what it will cost, they will take your old transmission as a core, the worst decision you could make is to let someone try to fix yours unless they can give you a definete estimate with no increase before starting the work, somehow I don't think they will do that.