You might keep him contained for an hour or two and see if after that he starts to put the foot onto the ground if this injury did just occur. If he does put it down on the ground, even if he doesn't put weight on it that might indicate a muscle sprain. If it is an ACL injury which sounds more likely than a dislocated hip, many owners wait until their regular vet is available since it is not life threatening. Since finances are an issue, you could try the aspirin and strict cage rest and see how he does.
The following sites sometimes help financially with vet bills.
This group helps low income families with vet care.
This organization help people with emergency medical care in some cases.
Quick application and approval for care credit card. You can sometimes apply and get approval while you are at the vet office.
American Animal Hospital Association
Helps animals that have been abandoned or if the owner is having financial hardships
Angels 4 Animals
This organization offers financial aid or treatment to those pets and owners in need.
God's Creatures Ministry
Help pay Vet bills for those that need help
The Pet Fund
Helps provide emergency vet care to those in need.
United Animal Nations
They help rescuers, low income and homeless pay for vet care.
UK Assistance with Veterinary Bills
For help in the UK.
Other Groups Who are Breed or Injury Specific:
Dachshunds Needing IVDD surgery
Dobermans (senior and special needs)
Sometimes helps handicapped pets.
LabMed: Rx For Rescued Labs
This site may have additional resources as well.
These vets may offer a free initial visit though you may have to pay for extra procedures and medications. See the next one for the coupons.