Same here - we have a lot of students and it is unfair to insist that they buy a gi early on.
Ueshiba insisted that you don't need money to practise aikido - and hopefully we can keep it like that (our club is completely non-profit making).
The way I see it is that the gi isn't for the instructor it is for yourself. A gi makes you feel better in your aikido and is more comfortable to wear (as well as giving you a stronger feeling of centre due to your belt) and making you think - right now I'm in aikido mode.
Also, you will find that your clothes begin to get ripped off your body when you start doing collar, sleeve or shoulder grabs. (I once had both my sleeves ripped off my karate gi in the same night - leaving me looking like an australian football player - best to get a judo/jujitsu/aiki gi).