How to make a really kick'n Tameshigiri stand on the cheap!
1 - 80lbs of concrete mix (I had 2 60lb bags on hand).
Use 1 or 2 buckets, depending on how many stands you would like, a drill and mixer. use about 30 to 40lbs of concrete per bucket.
1 (approximate) 60" PVC pipe cut in half, bevel the ID and OD to make it smooth so you will be able to shove the Tatami mat into the PVC without it catching on the edges of the ID, and shove the PVC into the bucket with the mixed cement. Use a level on the side of the PVC pipe if your concerned with it being perpendicular and support the PVC until the cement is dry.
Waite about 2 days for the cement to dry, and 12 hours before you would like to cut, soak your Tatami mat (immerse if possible). Then take the set-up outside and shove the Tatami into the PVC.
Have at it!
Cost break down
Buckets $2.60 each
1 3"X10' PVC pipe $13.20
1 80lb bag of cement $3.85
total cost is less than 20 bucks for 2 stands (only used 5'5" of PVC)