This seems like the holy grail and I will definitely do the free trial to test it out but at this point I am not getting paid for my website development efforts so I'm not ready yet to pay a monthly fee for this (just hacking on something for myself).
What I did (before I got someone to pay for it for me :D) was buy an iPod touch on craigslist. Got it for like $80. It was a big stretch, financially, at the time, but the hours upon hours it saved was well worth it. You can also sometimes pick up iPhones with bad esns/cracked screens for a lower than normal cost.
'Course all of that assumes you would need more than 2 months worth of debugging on browserstack.
It's a great product, unfortunately (for us) the price has been steadily rising. When I first signed up it was $20/month for everything now I think it's $40/month.