Well, TRAINING is a blanket term for a lot of things. I'll break down the various components.
1. School. In my area the schools/dojo's are few(less competition higher prices)but they vary between $60-$150 per month but that includes Karate/TKD schools as well as MMA schools.
2. Equipment. Weights alone equate a significant portion of this segment. Free weights vary dependant on where you buy them and size, but I've found they'r overpriced as shit, no matter where you go(approx $0.60 per pound). Buying the bench as well as a straight bar and two dumbell bars equates to another $300(approx). Buying a heavy bag alone is around another $100-150(a stand for one if you wanted it is another $100-150). Buying gloves as well as thai pads, and focus mitts equates to another $100-200. If you wanted to buy a mat thats another (approx)$100 for 5x10 ft. around $200-250 for a 10x10 space.
3. Apparel. Fighting related clothes are not limited to TapouT and Affliction. All sport related clothing is an option. Rash Guards, fight shorts, base layers, shoes. Each item listed is between (approx)$40-90. I like to support certain brands. Since almost all of my MMA gear is Everlast, I prefer Everlast clothing.
Now nothing listed in section 3 is compulsory, as well as most of section 2 is not as well, but much of it is tremendously helpful and should be considered. Suffice to say, training to be an MMA fighter isn't cheap by a longshot!