If I compare what you are contemplating for your first studio to my
own not-so-sound decision, I would say that it does sound very good.
Being in the high priced NYC area (after working for 2 1/2 years in
my apartment), I decided to overlook many worse things than the fact
that the water is down the hall. No heat, almost deserted 500,00
square foot building, the sink was a full city block away, illegal
sublet, freight elevator of dubious quality, unlit staircase,
desolate location, what was I thinking?? I ended up moving out two
months later. I now refer to that studio as "the dungeon". Oh, but
it did have a view of the entire Manhattan skyline....
Anyways, I think you should go for it. The interaction that happens
in studio buildings can be very positive. Also, it sounds
convenient should you wish to hold an open studio event or to meet
with clients (yes, you will have some of those soon!). I would say
that 75% of artists I know don't have sinks in their studio, except
for the ones in rather decrepit buildings who have taken it upon
themselves to do their own plumbing. Just get a little cart or
dollie to transport the water back and forth.
Anyways, don't worry to much about what you will do when you need
more space. Your situation may be quite different then. Better to
just get started working.