You can get crockpots pretty inexpensively. I saw one at walmart for around $18 I think, and there are usually a few at thrift stores and garage sales for much less than that.
Another option is there are different methods for hot processing. You can use the stove top double boiler method, put your soap pot in a slightly larger pot of simmering water, or you can use the oven method and put your soap pot in the oven to cook just like it does in the crock pot. Any of those will give you the rustic look you like.
If you are concerned about the time frame, you can CP your soap then cure it in the oven. Turn your oven on its lowest setting (170-180*), after you pour into your mold, put the soap in the oven. Some people leave the oven on for 30 minutes to an hour then turn it off, others turn it off immediately. Either way, leave the soap in the oven without opening the door overnight. I have never done this, you can do a search for more detailed instructions for this method.
Remember, whatever method you use, the soap will do better for sitting and curing for a while, so get started (if you haven't already) and good luck! Let us know what you decide and how it turns out.