I have a graco myride for my 1 year old (yes, she's rfing

) but I lost one of the harness covers that Velcro around the harness belt. She vomited on it so I removed them, washed them and now one is missing. I went to the website to order another set, and you can only buy the whole set for $40!!!
So I called to ask, because all I need are the two tiny covers, not the whole thing and she said "sorry it's sold in a set".
So my question is can I buy the ones at babies-r-us or ones off of etsy and use them? Or does that affect the safety of the car seat?
We only use them because she hates the straps being so tight but when they have the padding she is fine but now that it's off she pulls at it and screams so I need them back on ASAP.
Thanks!