The only other source would be to scavenge used machines. The TM price is fair and it's a nice small business run by folks who care for their craft. They will always give you their best (including free consultation on occasion). They've earned my business,OP--let them earn yours.
Tennis Machines is the best. I've sent them business many times and used them. I was really just hoping someone might have the entire extra bar for some unknown reason. I agree, $65 plus shipping isn't a bad deal.