Narmedeshwar/bana linga, means which has been made of natural narmada stone in form of lingam. Narmada stones are very cheap but are only stones which are blessed by lord shiva himself that all stones from Narmada River near Omkareshwar in MP are equal to my full fleged shiv lingams. Else you have to do pran-pratishta which is very cumbersome affair and cannot be used in home. When you do pran-prathista then shiv ling cannot be moved from the place of stapanna, as all rituals as per hindu vedic rituals are to be done as being done in temples. So you cannot place shiv lingam in home as you do sex, eat non-veg and do other natural calls in your home, so you not creating pure atmosphere thereby inviting lord's wrath unknowingly. PRANPRATHISTHA SHIVLINGAM cannot be removed from one place to another as even a cm movement will entail GOD'S PRAN-VAYU leaving idol at-once.Thats why I preach worshipping of BAANLINGAM (NARMADA) as SHIVA LORD blessed that he will remain in it eternally so there is no rules of movement of idol. Narmedshwar Linga are dark grey colour stones in a shape of lingam where on top there is one red patch similar to a man's lingam with a line joining from forehead to down. They are very cheap.you mostly get them in ujjain, om kareshwar or at haridwar. Costing from 50 rs to 500 rs at most depending on size. Size of lingam or any idol for home puja should not exceeed breadth of your three right hand fingers joined together. You can get from various websites selling the shiv puja items. Snake & Nandi is must with shivlingam always. Copper/silver/gold NAAG and Nandai of aast dhatu or marble stone is a MUST. If possible put Ganpati, Parvati & Kartikeya also in front of lingam. Parvati in centre facing shiv lingam. Ganpati on right side of Parvati and Kartikeya on left. Snake on Linga should face either north or east. Yoni part of Lingam ie. Place from where water poured on Lingam is drained - should face North or East.