How much would a bird checkup be for 2 birds?

I'm slowly earning money for another bird, but I have found a way to hopefully increase that amount pretty fast. I'm selling bird toys and playgyms that I make myself. ANYWAYS, since I have an income now, how much money should I save up for 2 birds' vet checkups, if they are healthy? I will earn more than that. I have a conure right now and I'm getting another bird, so I just want to make sure they're healthy and in good shape.