My eldest sister and her DH died within weeks of one another a few years ago. My sister was notoriously no-fuss; she loved a party but hated formality, and she hated spending money on what she deemed unnecessary things. She researched the subject carefully and determined that the most economical way to go out (if you'll pardon that expression) was to donate her body to a medical school. The school that she and her DH chose was a private one, and in exchange for medical use, the University agreed to pick up the remains from the place of death, and also paid for eventual cremation, though there was a delay of a few months before the ashes were returned. As her DH was an eligible veteran, both of them were interred in a single grave provided by the VA. The family held church-centered memorial services for them at the time of their deaths; as they were parishioners, there was no charge for that beyond a donation. I think that all totaled, the cost was around $600 for both funerals, so I'd say that my sister managed that very economically.
BTW, IME cremains usually come in a plastic box that is lightly glued shut, and once you cut the seal, inside that is a tied plastic bag. If you plan to inter them somewhere, an actual purpose-made urn is not necessary. For my MIL's interrment, I just went out and bought a pretty, inexpensive wooden box large enough to hold the entire thing and left the plastic container sealed. We buried the whole box. (It was about 12" x 8" x 8"). I think it cost around $20, and it looked nicer at the graveside service, which was the only time it was seen.