One air ticket, then what - a week or two in a cheap hotel if comes to worst and then 2 month deposit (I assume you will get back your deposit wherever you come from so that should help too..)?
At 25 I assume you are briging two suitcases and that's pretty much it....
First month will be tight till you get your first salary, then it's la Dolce Vita...
My opinion is that you should take the job even without a relocation package. You said it yourself, the pay is much higher than currently, the job is in the right direction and you'll get invaluable experience. The only thing is the moving expense which you don't have enough to cover.
For the rent deposit, some companies do offer a pay-loan, although obviously this is an expat thing. My husband's company did, repayable over 6 months I think. We didn't need it, but we took it anyway, the other half couldn't resist an interest-free loan.
This was on top of $72,000 relocation, plus airfares, plus 1 months accommodation and $200 daily allowance per person. Senior position though, but still just the airfare alone would be nice in your case.
Before I got laidoff, had a team-mate in the UK office looking to transfer to HK last years, he was offered similar package, and our VP was kind enough to dig deep for 3 weeks accommodation because it was internal-transfer, but could not get the relocation as UK guy was considered "not-senior-enough" by HR. Sadly he came back and insisted on relocation, which caused the Hong Kong HR to pushback and VP then rescinded the whole offer, and instead hired another new external guy who moved from Sydney to HK. Sydney guy got 2 weeks accommodation and nothing else.
So OP, you would need to think long and hard whether you really want to come to HK, at your own expense.
After nearly month of talking with both HR and the Director of Marketing, I've officially signed my contact to come to HK! It looks like there were communication issues between the DoM and Senior Management with the type of contract that was initially discussed vs the one that I actually received. Rather than getting a relocation package the company is giving me a pretty hefty signing bonus, which is great and I am aware that this bonus will be taxed.
Any who, thank you all for your comments and words of encouragement! Looks like I'll be in HK by the end of the summer, given my visa gets approved.