When you started making this quilt, what were your intentions for it? Was it for you? Or to sell? Or to give to someone? Or to worry about overpricing it if a dear friend wanted to buy it?
That's where I start when faced with that problem. If the dear friend thinks the price is too high, then she doesn't buy it. I have someone now who badly wants a Bow Tucks tote that I made. Not only can't she afford it, but she doesn't even carry a purse so I'm not giving in or going down on my price. She can use that money to buy necesseties....like food and medicine. She has to borrow money from friends and relatives every month as it is. I hope your friend isn't in that situation but if she can afford to pay for it in installments, then go for it.
I don't mean to sound cold hearted towards my friend. I give her plenty already. She is a compulsive buyer and often has to return something to have money to eat.