Unfortunately, $500 for a cockapoo is likely to get you a puppy from a backyard breeder or puppy mill whose parents have had no health screenings, is improperly socialized before coming to you, and may have behavioral or health issues. Cockapoos aren't really a breed, they are a "designer dog", and many "breeders" are in it entirely for the money and care little about the health and wellbeing of their puppies. Not saying there absolutely isn't a good cockapoo breeder out there....just that they're exceptionally hard to find.
If you're set on getting a dog, pick a known breed that meets your needs, because you'll be far more likely to find a breeder that is trustworthy and whose dogs have been evaluated by third parties for both health and temperament. You will pay a higher price. I would expect to pay anywhere between $1,000 and $2,000 depending on breed and location. But, know that when you pay that price from an ethical breeder (because unethical breeders might charge that, too) you will be getting parents who have been health tested (not just checked by a vet but tested for genetic abnormalities, hips, elbows, etc.), have likely been evaluated by a third party such as an AKC judge in something like confirmation, obedience, agility, therapy work, or maybe all of the above, and that the breeders have taken measures to socialize the puppies to common household things and give them new experiences even before they come to you.
If I were on a budget and wanted a cockapoo, I would make a list of the traits that attracted me to cockapoos and try to find a dog in a shelter that closely matched those traits.
Also, if you're young and still living at home and are planning to go off to college at some point, you better make sure your parents are going to be okay caring for a dog when you're gone. They do live for 10-15 years! It's important everyone is onboard when you get a new pet!