Could you post a sign at a grocery store or somewhere asking for large pots or buckets? I have a neighbor who puts really nice kitty litter buckets into the trash and I keep meaning to stop and ask her to save those for me. Our neighborhood is too far out to be on the recycle route so we have to drive recyclables 8 miles to put them in a large dumpster.
I have my advanced dumpster diver certificate...feel like I've won the lottery when I find a good bucket!
People with horses also have buckets galore, and sometimes restaurants will save them for you. The green pickle ones are really good!
When i moved my roses 6 years ago, it was the middle of a very hot summer, and I left as much dirt as I could around the roots and put them in big trash bags. (They were too big for buckets!) They lived that way for a few months...sitting in the shade by the house. They all did just fine.
I moved every plant I could possibly take, and I'm glad I did it. good luck! If I can keep them alive in Kansas, I'm sure you will do fine.