Mosaic tiles tend not to be very cheap. The production process for mosaic tiles is a lot more involved than for conventional bathroom tiles and this is reflected in the price.
Installing mosaic tiles is also not very cheap. The reason for this is that the wall preparation has to be perfect. Any bulges or imperfections in the wall will show through the tiles as the grout lines will highlight any irregularities. Preparation of the walls needs to be thorough for tiling and can involve skimming and plastering which will mean a substantial outlay.
An easy way to overcome this is to install mosaic tile effect wall panels. These are relatively cheap to buy (typically less than £20 per square mt.) and much easier to fit. They require very little in the way of preparation and can even be installed over existing tiles. As the grout lines are just part of the mosaic tile effect panel, irregularities are not highlighted as is the case with traditional mosaic tiles.