If you're 16 or over you could work some christmas hours in a shop. They're always looking to take on extra staff just for christmas!
Or as Tamara said, selling your old equine things which you might not use is a good idea to get some quick cash!
Go through your closet and stable locker, there's always stuff you haven't used in a year for which you can still get some money if it's in good shape 😊 saddle pads, breeches, shoes etc. You can also do chores, take on a few weekend shifts at your barn, muck out, plait for shows, clip horses, or deep clean and oil tack for barn mates...
See if you can use PayPal to pay and take advantage of the 6months 0% interest they offer