Regarding the costs,
Radar guns tournaments use to measure service speed reportedly cost between $5,000 to $10,000 and Cyclops, which calls the service lines is estimated to cost between $15,000 to $20,000 per court per week. The Canadian-based Auto-Ref line calling system, which has not yet met ITF accuracy standards, is priced at "$20,000 to $25,000 per court, per week, which is comparable to those prices and we are calling all the lines — not just one," Auto-Ref CEO Peter Szirmak told Tennis Week's Steve Flink in an interview last fall.
For tournaments which are a week long, the one-week price of hawk eye for two courts is somewhere along the prize money of one player who reaches QF (in Dubai, it is closer to the prize money of QF, other tournaments different). I think sponsors for many tournaments can come up with this money.