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Rent all the equipment yourself or browse on Craigslist for any cheap rentals.

Home Depot is typically the place to go to rent the machines - hope you have a truck or friend with one.
Any pictures of the lawn? Just curiosity.

Note: If you are redoing the lawn completely, removing the old sod - then no need for an aerator and dethatch (power-raking) at the moment.
1. Just removal the old sod
2. Maybe get a Roto Tiller to soften up the old dirt
3. Get some Top Soil and spread over it with the rake (Even it out)
4. Overseed and fertilize/lime
5. Water - and watch it grow.

Edit: you asked if enriched soil is fine - I'll tell you this, why spend over 150 dollars and hours to cheap out on 40 dollars worth of fertlizer/lime? It makes no sense lol, since you want to maximize the grass growth and health.

And you should start on this project soon, Spring is the optimal time to start.