If you're replacing exactly like for like, then the costs involved will include the shower enclosure - re-using existing tray or buying new - if latter, all appropriate waste pipes and fittings beneath shower - are you using existing water supply or going for new taps, shower-head etc - tanking and tiling, or scrubbing up old tiles - sealant gun and sealant.
In all of that you will have ranges of choices, so only you can really cost it up according to your taste.
But don't forget - labour costs will outstrip everything else. Which is why I do my own.