If you're not afraid of getting dirty or turning a wrench, do it yourself. Its not that bad.
You'll be removing your driveshaft, disconnecting any tailshaft supports (Usually a good idea to have it supported by a jack of some sort at this point.), disconnecting the speedometer sending parts, removing the tranny dipstick tube, various wires attached to it if any, removing lower bellhousing cover, use a flat head screwdriver (or the really neat flywheel/flexplate tool if you got one) to rotate the flexplate to where you can disconnect the three torque converter bolts that hold the TC to the flexplate, then you will unbolt the transmission from the engine block. You will want room to roll it out from under the car. It slides back off the dowel pins on the block, you lower it down and roll it out, put the new one on, do the opposite of what you just did. I might have left a few things out, but its not overly complicated and should be pretty obvious as to what needs to be done to make it happen. Just be careful when you have the transmission loose from the engine, finger mashing is just one of their unintended uses (grin).
I bought three foot long extensions and a U-joint adapter to make my life easier with the bellhousing bolts that connect to the block. I was swapping out a 700r4 transmission and found this was the easiest way to deal with those bolts.
Hope this helps.