I have two with the same problem but it is not slowing them down whatsoever. And I have one with no problems. I haven't incurred a lot of vet bills with any of them including the two with problems, it's just routine maintenance stuff for the most part. Mine have pulmonic stenosis so they have to have yearly echos ($300) and they take Atenelol twice a day ($12 for 90 pills) and that's about it. The biggest cost incurred so far was the angiogram and that was around $800.
Please don't let this scare you off, just research the breeder you are planning on getting one from first. I would recommend rescue first though. Sometimes those dogs come in with health problems but before they are adopted out the problem is either fixed or well on the way to be.
Good luck and no matter what you decide glad you found us