I went to a conference in Canada during my part-time PhD. I can't work, and have no income, but my husband has a good income. Didn't stop me applying for financial help though. We couldn't really afford to pay for additional PhD costs on top of those already there. So I applied for a travel grant from the conference organisers, and got that, $US 500, which paid for most of my transatlantic airfare. And I asked my department if they could help too, and they gave me 100 pounds, which covered my conference fees. I still had to cough up for accommodation, though staying in student halls of residence kept that cost down. And we had to pay for my husband's travel costs too, as my carer due to disability reasons. But we weren't as out of pocket as we could have been.
The moral of the story is go for it!