Its really hard to get a hotel that is very close to HK international airport because its in an Island. even if  u get a hotel there around the price might be high. I think the best option for u is to get a Bus either A21 or train to Jordan or Yau Ma Tei. There you can get hotels for around $400 HKD and you gonna love that place as you can see many Nepalese community and cahal pahal.


Regards