Hello I have a 2004 Hyundai elantra GLS. Has 4 wheel ABS, no traction control. I went to a tire service plus center that has helped in fixing break. I had a grinding sound that lasted around 3 minutes during the morning while driving, and my break fluid was running out rather quickly, and the area beneath the reservoir looked wet. I took it there and they said my break master cylinder needs to be replaced. I went for a second opinion and cheaper pricing (they would charge $300).

I went to a second smaller mechanic and he told me to press my breaks and he said hey, let me show you what happens when you press them. I looked under the hood as he did so and I saw a valve squirt break fluid then proceed to trickle until he took his foot off. He said the cylinder looks fine but the valve along with another one as well should be replaced as one was leaking and the other looked wet. I saw a video of a similiar looking valve that was replaced on an 02 hyundai elantra and the replacement valve did not have the black seals like the one on my car.

Are there more ways I can tackle if I should go through with the cylinder or the valve changes? The second mechanic told me the valves do not come with the cylinder purchase and I can only get them from Hyundai or a junk yard.

 

This is what I would suggest and here is why.
Since you depend on the brakes working whenever you need them, considering it is a 2004 vehicle , get both the master cyl and valve from the dealer .
Now you need to decide if you want to replace those parts or have another shop do the job.

There is a special procedure to be used when replacing a master cyl, and you will need a scan tool to bleed the air out of the ABS modulator assy.

If you have the equip and know how it is not that bad a job. Since you may be limited there, it looks like you may need to go the full route.
I wish I could suggest a cheaper route, but when you step on that brake pedal and it won't stop it could cost a lot more than having the job done correctly..