Do you have an old navy near you? I've found that some of their plain summer dresses work well for nursing even if they are not "nursing" dresses. They are either v-neck or have enough give in the neckline to pull down. They're not formal, but with a necklace, heels and a cardigan, I think they're funeral appropriate.
I got a black dress from Target for G's baptism for around $30. It was the kind that has the spanx like undergarment built in. It was low cut stretchy material so I wore a nursing tank underneath and had no problems BFing in it.
Re: Nursing dress for funeral?
I recommend a top and a skirt. That is the only thing that works for me. I don't use my nursing cover anymore and the 2-piece worked for me.