How big is your bathroom and what all are you talking about doing? We redid our kids bathroom in our last house about 4 years ago. Standard sized jack and jill bathroom that was split into two rooms (vanity in one toilet and tub in the other). I took out the divider wall myself, the old toilet, the flooring (which was carpet), the old tub and tub surround. That saved us some money right there. We reused the same vanity (painted it) and counter top (refinished it). We then had plumbers move the toilet over to make room for a bigger tub (concrete slab so this was not a small task). They then did all the plumbing work for and installed the new, larger tub I bought. We then had people do the tile work for the tub surround and floor. After that, it was painters fixing all the drywall (there was painted wall paper they had to take down, then texture and paint). New fixtures, lighting, mirrors. We picked out and bought everything our self (paint, fixtures, tub, toilet, tile, grout, calk, etc). When it was all said and done, we spent maybe $5k-$6k. Granted, you throw in a new vanity and counter top and that could jump the cost a couple of grand or more. The point being, $25k seems absurd to me. Yes, a big walk-in shower alone can get pricey if done right, but you can get by on much less.
Oh, and if you are concerned about resale value, skip the pre-fab showers. Most home buyers want tile and will not see that as any kind of added value. As for the grout and mold, if the tile people actually do proper water proofing (kerdi, red guard, or the like), then that is not really a problem. Water proofing directly behind the tile will allow it to dry out properly in between use.