Small equipment--say less than $1000--I think should pay for itself in about a year. Say you buy a spreader for $400. For using it you pay yourself $20 per hour, plus 50 cents per hour equipment charge, (plus various charges for profit, overhead, fert and cost of driving to the site). If you did 5 lawns per day at one hour each--you would have charged $2.50 for the spreader per day. It would be paid off in 160 days. And...the charge compensates you for the upfront cost and the risk of buying it before you had the work in hand. And...in theory...allows you to buy a new spreader when it wears out. It also compensates your for maintenance cost for the spreader--grease, oil, new impeller and the labor time to apply these.
Of course, with a bit of luck, in year 2, 3, and 4, you will have a paid-for spreader...and can charge the customer for the time, and pocket the $2.50 per day cash.
As for the price vs quality--that is a judgement call. You want professional equipment--3/4 ton truck--not an S-10. Lighweight equipmnet doesn't cut it. And you want to look professional in the customer's eyes.
I once lost a customer, because I did an insect job for leaf-hoppers with a hand sprayer instead of my skid sprayer. Didn't look professional. Naturally, I would have had to use up the product in the tank, and go back to the shop with the truckfor a refill with insecticide.