It's a factory fault with the rack, the seal is prone to destroying itself unfortunately.
I've had racks rebuilt over the years only to start leaking again 2-3 years later.
Some do, some don't.
If it's not bad, then just leave it for now IMO and don't do it until you absolutely have to do it.
The more expensive place might actually be modifying the rack, rather than simply rebuilding. You can apparently mod the seal so it is less prone to failure.
Unsure of what that involves etc. I'd imagine it would make repairs more expensive.