I don't think you would need to spend $900.00 to get everything you need. I've done hot blueing at home and had good results. Since you are only doing a pistol slide you will only need small tanks.
Ditto the prep work! I usually start by stripping the gun down and cleaning everything with a good degreaser. That's followed by a long rinse. Then into an acid bath (I use muratic acid) to kill the old blueing. Another long rinse and you can get started. At this point you should have all white parts with a dull finish. File, sand, machine and polish the parts to get the finish you want. What you see in the white is what you will get when blued.
Now you have to clean everything again. Every spot of oil, wax and grease must be removed. Wear cotton gloves. Any mistake here and you blueing will not look good.
You must use the time and temp recommended for your blueing to the letter. The fumes can be terible but contamination is easy if you do this outside. The pros use vent hoods. You will have to make some choices here.
Once the blueing is done you will neutrilize and then oil the parts.
Now you will be disappointed. The color will not be the same as the original finish. It will be good, but not like the original.
An other method is rust blueing. This requires a LONG time to finish. You allow the parts to slowly rust and card them each day. In about a month you will have a deep blue finish very much like the original. The problem here is that you can contaminate the parts and ruin the finish or let the rust go too far and ruin the finish. I've never tried this method, only read about it.
Black oxide (the finish you say you don't want) is a lot easier. With a nicely polished gun it gives a glossy black finish that is hard to beat for the backyard gunsmith.
Many of the older deep blue factory finishes can not be duplicated today. EPA regulations have put an end to them because of the gasses that are released.
Good luck with your project.