For the 12 years my Cocker Spaniel was with us, I trimmed her hair myself. I had bought an Oster A5 from Pet Smart, it works great, it's professional and heavy duty. It comes with guards so you don't cut too close, but after you get good with it, you won't really need them.
I just checked and Chewy and Amazon are out, but I found them for sale for $120 on eBay in stock in Georgia, which is cheaper than those two.
Oster A5 Turbo 2-speed 78005-314 Professional Animal Dog Pet Clipper 10 Piece for sale online | eBay