... "I cannot imagine recovering from a TKR without an ice machine. " ...

I recovered from both my TKR's with only flexible ice packs sent home from the hospital and never felt the need for an ice machine which I did sometimes use at the end of official PT sessions. I liked taking my simple ice pack to bed, to recliner, to sofa without dragging extra stuff around, plus getting up to fetch and carry it to re-freeze gave me another reason to get up and move around. Some active movement every hour and using the knee frequently are the key to quick recovery, and while an ice machine is convenient, you can achieve the same results with ice packs if money is an issue.