I don't know how affordable you will think it is, but we bought one of the stainless trash cans from Bed Bath & Beyond (made by SimpleHuman) that has the step pedal with a hinged lid. The back is flat and the front is rounded, so it sits flat against the wall will a rounded front. It has a hard plastic liner that lifts out, and they sell "special" bags for it, but we use regular old 13 gallon Hefty Kitchen bags in it just fine. We used to keep our old trash can in the pantry, then we moved and didn't have a pantry in our rental unit. We have a German Shepherd (she can open doors too... lol.. smart pups, huh?), so we had to figure out how to keep her from getting something she shouldn't have. She has never bothered this trash can.
It runs about $100, but with their 20% off coupons, it was only about $80. My folks liked it so much (it keeps the smell down, too, if you don't empty your trash very often) that we gave them one for Xmas the next year. They loved theirs so much, they gave one to my brother and his wife! We have had it for almost 5 years now, and it still works perfectly.
Hope this helps.
http://www.bedbathandbeyond.com/product.asp?order_num=-1&...