I am not familiar with Indiana geography. However, you are probably near a Target, Home Depot, Lowe's or Walmart. As the holidays approach, all these stores will have them. Most will have plenty left after the holidays at a greatly reduced price, but that's another story for another day.
If you can not wait that long, your best shot might be contacting a local nursery.
I agree with wanting to buy plants in person and not on line. However, I am in a major metropolitan area and availability is not an issue for me.
In terms of starting, also known as rooting, cacti, knowledge is the key. Not much different than learning how to drive with a stick shift. If you do not know how to operate the stick shift, the car isn't going to go far. What I am trying to get at here is if you do not know how to do it, you can not expect success immediately. Trying to root cactus can be tricky. It is much easier if what you are trying to start has roots. I assume your pieces did not have roots.
Pieces of cacti that do not have roots are very susceptible to rot, especially if they have not had an opportunity to "harden off" or "calous over" on the bottom. This is there one defense against preventing moisture from entering. If they were still soft on the bottom and were watered, this is why they rotted. If they had roots, the roots could absorb the water and help the plant grow.
In conclusion, please do not view my comments as condescending or scornful. Not intended in that light in any way. Notice I did not ofer any advice on how to root Christmas cacti, I do not know how. However, I have attempted to give you some basic information on cacti care. I, too, have lost plants this year to rot, it is not something that happens only to first timers. I hope this helps. Good luck.

I agree. In about six weeks you will likely find them popping up at the big box stores. I recommend that you snap them up as soon as they are available. You'll pay a little more but they will be healthy. After WMart tortures them for 3 months you may not be able to resurrect them. Try misting the cuttings instead of watering the soil. They have no roots and cant absorb it.

Usually when a squirrel or bird or whatever is in one of my pots and breaks off a piece of my holiday cacti, I just pop the piece into another area of the pot and it roots...when I am trying to do it indoors, I will use as small a pot as possible and have had more luck with single segments. Let them dry out for a few days so that the cut will callous over, then plant in fast draining soil( mix lots of perlite or small chips of orchid bark in your potting soil )Water the mix first, then pop the cutting into the soil so that one third of the segment is below soil level. Don't let the soil dry out too much, I would say wait till it is about 80 percent dry before watering again. Mist regularly.

In their natural enviroment these plants grow in trees, getting their nourishment from moss and other plant debris that collects in the areas between branches of the trees etc. They don't like their roots to be in a heavy soil, it's not natural to them. Keep the soil light and fast draining and they'll be happy.

After at least a few weeks, try tugging very gently on the segment, if you feel any resistance, it is probably rooted - if not, keep on with the routine.

In the next few months you will be seeing alot of them for sale. If you don't, let me know and I will mail you some cuttings after my plants bloom in the fall.

Also, please keep in mind Home Depot and Lowe's guarantee their plants for 1 year after purchase. They will not guarantee their clearance plants. I am not sure what Walmart and Target plant guarantees, if any, are.