In 15 years, my dad has worn out 3 roasters. 1 was shit to begin with.
I buy something like 80lbs of coffee a year and he also does. My guess is 500lbs or so and the roaster is tired. Last time I bought green coffee it was $6.30/lb. Local roasted coffee is around $15-20. Roaster is $450. At a savings of $10/lb without counting electricty, time or effort it takes 45lbs to pay for itself. To be conservative call it 90.
All that being said, do NOT do it for savings. Time is money. Instead do it for flavor. And there you can win big time. Even the local roasters can blow me.