There is no set price for any accessory, and we would never put a price on the item you are after. The only thing which we would recommend is setting a budget and sticking to it, but also recognizing that you get what you pay for. There is no point in buying the cheapest accessory you can find to save yourself some money, only for it to fall apart a few weeks later. Our recommendation is to always spend a little more to get an item which is higher-quality and one which will last you for a long time. It is better to save up for one quality item than to buy multiple cheap items.
Having said all of that, you can save yourself some money by shopping around for the best deal. Of course, we have already done that, so an item from our list is not only a high-quality item, but it is at a price which you will find hard to beat.