I list items on ebay and I don't use the reserve price option. The reserve price guarantees the seller an amount they're probably willing to sell the item. I prefer just listing the amount as the opening bid. If the item doesn't sell, the seller can do a 2nd chance offer to any bidders, but that's unlikely at 1/2 the reserve price. As far as cost, ebay usu. doesn't charge anymore based on your opening price, unless you do buy it now or fixed pricing and add extra bells and whistle options to your auction. They get you on the actual sale price if the item sells. Also, the more you sell, they give power sellers discounts too, so reserve pricing is a surcharge option, but may be a free option for power sellers. I don't sell that much, so I'm too far away to get any discounts.
RE: ebay feedback, seller feedback is usually honest, but I can tell you I'm missing 40% of my sales feedback because buyers don't bother to leave any. Buyer feedback is pretty bogus IMO, as you can't leave any non positive feedback if you get a bad buyer. I just had one buyer pay for US Parcel Post and asked I ship promptly, so I gave him Priority shipping at no cost and got it to him in 1 day. After tracking stated the pkg was delivered to him, he immediately filed a claim to ebay stating he wanted a refund. So I had to supply all my tracking info and was about to file a claim for USPS insurance. The buyer waited about 1.5 days to close the case and said it was delivered to the wrong address. Most people that don't get a pkg will usu. send me an email first before filing a claim this fast. I think this buyer assumed I sent it US Parcel Post that had no insurance.