I've heard good things said about the once was Simrad but now Raymarine Tiller Pilot. Not sure how many amps the TM sucks up but I'd have thought the newer designs like the TP would be more economical to run.
Mate of mine with a tiller steered VDS34 (the Womboat is VDS34 wheel steering) has a TP and when we sailed her up to Lake Macquarie last year it performed faultlessly.
Dollars of course may well be an issue.
“Give a man a fire and he's warm for a day, but set fire to him and he's warm for the rest of his life.” Terry Pratchett