It has always been the practice that artists should have their own art studios, and most artists think that it could be expensive if they have to have rent one outside their homes. The best thing to do would be to look for a place large and affordable enough where one or two of the bigger rooms can be easily converted into a studio. It is not very hard to do once careful thought and considerations are taken objectively.
First of all, what type of artists' studio is it going to be? This makes a lot of difference as having easels and paints do not take up much space as compared to sculpting using blocks of marble or tons of scrap material. Knowing what kind of studio is needed will put a firm hand on the budget that would have to well thought out.
If it is sculpting and there is a need to make a lot of noise, consider having it outside of a rented or owned home instead of an apartment. Neighbours can get cranky if the artist is in an artistic pounding mood at one or two in the morning. Painting, however, is a much quieter activity and a studio can be set up anywhere in the apartment, as long as there is enough light.
Some artists do not consider painting their walls colors that may distract them, but this really just depends on the artist. If the artist is one who likes to set a mood to a particular project, then they can always do that by painting the walls in the colors which will enhance the art rather than detract it. Others simply like white walls or cream walls as they are neutral colors and will serve as a display wall also.
Some artists may need a sink in their studio. Others need a full bathroom as they may just live and breathe in it once the muse sets in. An industrial type of sink would do well for a lot of artistic forms and it is also convenient to use because they could easily be cleaned compared to the neat and tidy porcelain sinks that would just get ruined by the various materials that are used by the artist.
The most important thing to consider would be the amount of light in the room. Painters need good sunlight because of the obvious reasons; some sculptors don't really need the natural sunlight to work and could just depend on it as well as a fluorescent lamp. There are T5 lamps that are cool and economical to be considered. To widen the spectrum somewhat, there are also T8 and T12 lamps.
Then there are the supply racks to consider. Think about what is needed to hold the materials or supplies used in a particular art. Some do not need tables others may need two or more. Some sculptors need shelves and boxes to stow their equipment in and some just lay them on a table.
Last to consider are the furnishings. Artists' studios do not usually look like a picture from Architectural Digest. A simple chair or stool and probably a folding table would suffice. Some artists forget that they have backs and may totally ignore the stool. Some simply lie down on the floor and pass out tired because they are too tired to go to bed, so a simple bed in a corner would be appreciated. The folding table would be used when they do finally remember to eat.