If you do go through with this do not, DO NOT, skimp on the little luxuries. Make up for the lost bathroom with a really nice on. Get the high end (best you can afford) tile, heat the floor tile, get a really nice vanity (as budget will allow), ensure HVAC is sufficient, ensure proper ventilation, if glass shower enclosure use seamless glass (expensive but really does pay dividends for resale and oh so nice), add proper lighting, get a good flushing toilet, add adequate sound deadening/insulation, and get a nice SOLID CORE DOOR (don't want to hear people during their business). If the main bathroom a tub is really needed so child, especially infants can be bathed.
Take a moment and actually add the costs up before you decide. Although the missing bathroom can effect overall value, a really well done NICE bathroom can over come some of it. On the other hand if you make a really nice bathroom and it outdoes the rest of the house buyers will feel it is too nice and may make them wonder why it is the only really nice room.
Some of this is from personal experience and some from my home buying quest/realtor passed pointers. When I redid my small master the two things I passed on because of the added costs was in floor heating and seamless glass shower surround, now every day I cuss myself for not doing it. Oh and don't forget storage space. Several of the houses I walked into had great bathrooms with ZERO storage space and that is big turnoff.