1995 Toyota Camry Help please

I have a 1995 Camry (145K miles). The engine runs very smoothly. Last week, my brake started to leak badly. I pour the brake fluid in and it empties in 20 minutes.
The mechanic examined the situation and told me that the ABS Unit is leaking fluid. To replace the unit cost $750 plus tax. To install will coast another $200. My mechanic told me that it might last for another 3-4 years. Question: Is it worth it?
I kept my Camry well with regular servicing. Will the ABS unit brake again? Does a used ABS unit cost $750. I live in Cincinnati. Thanks for your advice.