Older Macs won't support the latest OSX and XCode.

I'd look at MacinCloud or something similar if you have good bandwidth. $50 / month for 24x7 online access to a Mac isn't bad at all and they have pay-as-you-go for about $1/hour. I haven't tried them, but I think I've even seen people claiming to do iOS development there using an iPad (+keyboard) as their physical interface. You can get a few friends with iDevices to join Testflight for free physical testing.

http://www.macincloud.com/pricing/ http://XCodeClub.com http://virtualmacosx.com/