Absolutely get a used truck. I picked up a 91 Ford F-150 XLT last February off of ebay. V8, manual, 4WD, bedliner, extra leaf springs, just 71,000 miles on it with 6000 on the engine. Paint is really decent. I paid a premium for it at $3600. Except for horrible gas mileage, nothing yet has gone wrong with it. The truck gives a good impression. I'm completely happy with it, and it was so much less than a new truck.
My previous truck was an under-powered 86 F-150 6 cylinder junker worth about $50
My customers didn't care what my truck looked like. They cared what their lawn looked like. It was my only truck from 1991 till 2005 and it got the job done. No radio. No AC. Had trouble going up hills with a load (full 6x12 trailer).
All youngsters want a new car or truck. It's a very common financial mistake for people just starting out. (The value is in buying used automobiles.) Usually, no matter what the older/wiser say, the young still go out and enslave themselves to new car payments for 5 years or so.
However, it's okay to buy the best you can afford in equipment.
By the way, I still have my old 86 F-150. It looks like crap, but it runs perfectly. It's my back-up truck for when the 91 breaks down.