Please help us save Koda

Koda is a 3 month old German Shepherd - Lab mix. We got her about a month ago to train her as an Emotional Support Animal and we just found out that she is very sick. Our vet tells us that she has a grade 4 or 5 heart murmur and that she wont survive very long if we don't find a way to treat her. We love her so much and we need help to save her. The visit to a Cardiologist alone is between $500-$800 not including scans and treatment. Pet insurance companies won't take her either because it is a pre-existing condition. We love her so much and need to save her...