Me too, I'm so sad about it. I don't always have access to funds like that either, so I only ever bought one Balenciaga a year from when I first got into them in 2010. Although had I known they would discontinue G21, I might have made a more conscious effort to get maybe one or two more! I am also massively into my make-up (unfortunately not the cheap brands either!) and also jewellery, so bags are not my only vice, hence why I usually stick to one Balenciaga a year!
I wasn't impressed with G12 when I heard about it, but I am usually a sucker for anything new and usually end up liking something new even though I initially insisted I'd hate it (like with every new iPhone that's ever come out, for example!) but that never happened with G12. Even when not shopping for a bag, I'll go into Harvey Nics when out shopping just to look at the G12, sort of hoping that I'll finally click with it and even though I can appreciate they're nice bags, I ALWAYS end up seeing one and thinking 'that would look so nice in G21' and that's what makes me realise I don't really like it enough to buy one.
Maybe I'll just have to build up my bracelet collection from now on instead! At least it will be cheaper!